bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Chemoreceptors of the Wireworm (Agriotes Spp.) and the Relation of Activity to Chemical Constitution
Authors: Crombie A. C. , Darrah J. H. 
Published: April 2021

ABSTRACT
This paper continues the work on the responses of wireworms (Agriotes spp.) to chemical stimulation, published in a previous paper (Thorpe et al. 1947), by a further analysis of the relation of activity to chemical constitution and of food finding, and the investigation of the anatomy and physiology of the chemoreceptors. Substances present in food plants elicit two responses in wireworms, orientation and biting. There is a clear distinction between those compounds which cause only orientation and those which cause both biting and orientation. In almost every case the former have high activities (9 − 11) while the latter have activities of less than 3. All the biting compounds tested for orientation have proved active, the threshold being similar to that for biting. Substances causing orientation fall into two classes, viz. amides and urea derivatives, and dicarboxylic acids. In view of the small number of compounds tested the two classes of active substances should be treated with reserve. In the first, it seems definite that the amide group is responsible for activity. But while all the other compounds found to be active fall into the second class, i.e. are dicarboxylic acids, it is by no means true that all dicarboxylic acids are active and no rule is apparent for predicting whether a given dicarboxylic acid will be active or not. Substances causing both orientation and biting summate when either response is tested. The following pairs of substances summated when tested for the responses indicated: glucose and sucrose for orientation and biting; glucose and peptone, glucose and triolein, peptone and triolein and glucose and tannin for biting. Orientation occurs in a gradient of concentration of which the steps are formed by different substances, as well as when the steps are formed by one substance as was shown in the previous paper. Active substances are secreted in small amounts by the roots of growing potato plants. These would explain the orientation of wireworms to the roots of growing plants (e.g. wheat). It is thus likely that the root system forms an extended trap along which wireworms may be led to the grain or tuber in the centre, where a wound caused by their random biting would release active compounds in sufficient concentration for them to remain and feed. The biting of glucose is inhibited by a number of substances, viz. lead acetate, quinine, allyl-iso-thiocyanate and common salt, as well as by acid and alkaline solutions. Common salt also inhibits orientation in glucose, but not in asparagine. The chemoreceptors which appear to be involved in these responses are of two kinds : peg organs, located on the labial and maxillary palps and galeae, whose stimulation leads to both orientation and biting; and a cup-shaped sensilla on the distal segment of each antenna, whose stimulation leads to orientation only. Both asparagine and glucose stimulate both kinds of receptor.
The Functions of the Corpus Allatum in Rhodnius Prolixus (Hemiptera)
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
It has been shown in earlier papers (Wigglesworth, 1934, 1936, 1940) that metamorphosis in Rhodnius takes place when the corpus allatum ceases to secrete the ‘inhibitory’ or ‘juvenile hormone’. There was no evidence for the existence in this insect of a ‘metamorphosis hormone ‘which promotes the development of imaginai characters. Growth and moulting are induced at all stages of development by a ‘moulting hormone’ (what is called by Scharrer & Scharrer (1944) a ‘growth and differentiation hormone’) secreted in the dorsum of the protocerebrum. When this hormone alone is acting, the latent imaginai characters are realized and metamorphosis occurs. When the ‘juvenile hormone’ from the corpus allatum of the early nymphal stages is present in addition, it causes the preferential development of nymphal characters and thereby suppresses those of the adult.
The Physiology of Echinus Esculentus Spermatozoa
Authors: Rothschild Lord 
Published: April 2021

ABSTRACT
The O2 uptake of Echinus esculentus sperm suspensions is strongly inhibited by CO. In equilibrium with a mixture of 90% CO and 10% O2, the O2 uptake is 60% less than that of an identical suspension in equilibrium with 90% N2 and 10% O2. This inhibition is completely reversed by light. Spectroscopic examination revealed cytochromes a, a3, b and c. On treatment with CO the spectrum of COa3 was observed. These results establish that the cytochrome system is the catalytic agent which controls the respiration of sea-urchin spermatozoa. The O2 uptake of sperm suspensions in equilibrium with 90% N2 and 10% O2 is about 10% lower than in air. Certain difficulties in measuring the R.Q. of sperm are discussed. The reversible effect of CO on the O2 uptake of spermatozoa is the same whether they are in egg water or sea water.
Anaphase Movements in the Living Cell
Authors: Hughes A. F. , Swann M. M. 
Published: April 2021

ABSTRACT
The anaphase movements of living embryonic cells of the chick in tissue culture have been studied in phase contrast illumination, and in polarized light. Cine photographic records of chromosome movements and spindle changes have thereby been obtained simultaneously. Chromosome separation in the chick is made up of two components a movement of chromosomes towards the spindle poles, and an elongation of the spindle as a whole. The assumption is made that the force acting on a chromosome is directly proportional to the velocity with which the chromosome moves. If this assumption is accepted as an approximation, it is possible to interpret the relationship of chromosome velocity to chromosome separation and spindle-fibre length. This leads to the conclusion that anaphase movement is due, not to repulsion between chromosomes, but to a contractile mechanism operating from the spindle poles. Polarized light studies indicate that the orientation of the spindle material is high at the poles, and weaker at the equator. There is a small aster at either end of the spindle. The centrosomes are interpreted as centres of an orienting force, which build up the contractile mechanism of the spindle from isotropic protoplasm. It is suggested that asters may also be contractile, and cause elongation of the spindle. The inadequacy of the old conception of spindle fibres is discussed in the light of more modern views on molecular behaviour.
Laboratory Studies on the Egg of the Blowfly Lucilia Sericata (Mg.)
Authors: Davies Lewis 
Published: April 2021

ABSTRACT
The chorion of the Lucilia sericata egg is shown to be composed of two main layers, both of protein ; the outer can be tanned by p-benzoquinone, but the inner is apparently already tanned. The chorion and the chorionic vitelline membrane are both lipidized shortly before the egg is laid. This makes both structures more rigid, but does not waterproof the shell. After the lipidization process is completed, a lipoid waterproofing layer is laid down by the öocyte, between the chorion and the chorionic vitelline membrane. This waterproofing layer has a critical temperature in the region of 38 ° C., and can be damaged by an abrasive dust, emulsified by the detergent I.C.I. C09993, and removed by chloroform at 30 ° C. in 12 hr.
The minimum humidity for development of L. sericata eggs at 37 ° C. has been found to be 50 % R.H. At 1 − 2 ° C. above this temperature eggs require about 80 % R.H. to complete development. Eggs at 37° C. can withstand fairly long periods of humidities below 50 % R.H., provided they have not been previously incubated in saturated air at that temperature. The latter treatment, even if continued for only 30 min., makes eggs far more susceptible to desiccation when subsequently incubated at a low humidity.
Fully developed larvae can survive imprisonment within the egg-shell for about 3 hr. at 37 ° C.
Observations on the Development of Lucilia Sericata (Mg.) Eggs in Sheep Fleeces
Authors: Davies Lewis 
Published: April 2021

ABSTRACT
Comparative determinations of fleece atmosphere R.H. using cobalt-chloride papers and paper hygrometers showed that the former were reliable, although their use was subject to a limited humidity range (40−70 % R.y.). Determinations made by means of wool samples were found to be subject to large positive errors, since the wool near the skin did not appear to be in equilibrium with the fleece atmosphere. Measurements of fleece R.H. by cobalt-chloride papers on twenty-eight sheep of various breeds showed that the R.H. varied considerably from day to day in individual sheep, and in different sheep at the same time. The common condition was one of low R.H., unsuitable for the development of blowfly eggs. R.H. measurements and a study of the fate of L. sericata egg batches placed in fleeces showed, however, that conditions suitable for development were occasionally experienced in these sheep. Humidities high enough for hatching were more rarely found. Rapid secretion of watery material by the skin (sweating), leading to suitable humidity conditions for strike, was detected. The various sheep used showed great differences in sweating rates, the most rapid sweating being found in two Down Cross lambs where, at one period, the limiting factor for strike must have been that the blowflies were not attracted to them.
Studies in the Respiration of Paramecium Caudatum
Authors: Humphrey Beverley A. , Humphrey George F. 
Published: April 2021

ABSTRACT
The lack of specific enzyme studies on protozoan material may be attributed mainly to manipulative difficulties. Burge & Williams (1927), in their substrate-utilization study on Paramecium caudatum, stated the position as follows: ‘The most difficult part of this investigation was the raising of these organisms in sufficiently large quantities and in fairly pure cultures.’ The slow advance of our knowledge of the nutrition of most types of Protozoa has left the position substantially unaltered. A few cultures of Protozoa on defined medium in the absence of other living organisms have been established (Doyle, 1943). Notably Chilomonas (Mast, Pace & Mast, 1936; Hutchens, 1939) and Tetrahymena (Kidder & Dewey, 1945) have been grown in a culture suitable for metabolic studies; many types have not been cultured free from their living food organisms, e.g. Amoeba and Spirostomum, and the bacteria-free culture of Paramecium of Johnson & Baker (1942) has a division rate so low as to render its use in metabolic studies impracticable.
The Absorption of Volatile Fatty Acids from the Rumen
Authors: Gray F. V. 
Published: April 2021

ABSTRACT
In a previous paper the relative rates of absorption of acetic acid and propionic acid through the rumen wall were discussed (Gray, 1947a). While the manuscript was being prepared, Danielli, Hitchcock, Marshall & Phillipson (1945) described a series of experiments from which it was evident that the lower homologues of the fatty acids are absorbed through the rumen wall at different rates when the rumen contents are acid, and that the relative velocities of absorption fall in the series butyric &gt; propionic &gt; acetic. The observations made in this laboratory (Gray, 1947 a) independently and by different methods were in agreement with these conclusions. There is therefore no reason to doubt that the higher homologues are absorbed preferentially when the rumen contents are acid.
The Experimental Induction of Prenatal Mortality and the Subsequent Elimination of the Dead Embryos in Rabbits
Authors: Rogers Brambell F. W. , Henderson Megan , Mills Ivor H. 
Published: April 2021

ABSTRACT
All the embryos in utero in pregnant rabbits were killed in a few hours by 5 mg. of stilboestrol administered subcutaneously. Experiments were performed on fourteen animals at 11 days, twelve animals at 1534 days and three animals at 19–20 days post-coitum. Embryos killed with stilboestrol administered at 11 or 1534 days post-coitum were invariably reabsorbed. Abortion occurred when the embryos were killed by stilboestrol at 19–20 days. Some or all of the embryos were killed in sixteen animals at 16 days and in five animals at 19–20 days post-coitum by perforating the uterus, membranes and embryos with a needle at laparotomy. Many of the embryos survived this treatment. Abortion occurs as a rule, but not invariably, when all the embryos are killed by surgical means. In the 16-day-series abortion is probably preceded by an initial period of autolysis. In the 20-day-series one animal reabsorbed but the others aborted. Destruction of some only of the embryos at 16 or 20 days post-coitum by surgical means usually results in reabsorption of the dead embryos and the maintenance of pregnancy, but may result in abortion. The occurrence of abortion may depend on the stage of development attained by the placenta. Abortion occurred at 1912-25 days post-coitum. There was no evidence that abortion occurred before the 19th day. The speed at which reabsorption proceeds varies with the stage of development of the embryos at the time of death, the manner of death, and whether some or all the embryos die. Reabsorption proceeds much more quickly after stilboestrol administration than after surgical interference. The dead embryos are much more persistent when others survive and the mother remains pregnant than when all are killed surgically. It is uncertain whether the greater rapidity of removal, when all embryos die, is due to more rapid autolysis or is due to the curtailment of reabsorption by abortion.
The Activity of Ram Spermatozoa
Authors: Rothschild Lord 
Published: April 2021

ABSTRACT
Concentrated suspensions of active ram spermatozoa exhibit periodic changes in their electrical properties when these are measured in an a.c. bridge. Suspensions containing immobile or feebly active spermatozoa do not exhibit this phenomenon. The frequency of the changes has the following characteristics:It is maximal when the suspension is fresh, and declines to zero after some 60 min. at 37°C.It can be maintained for about 20 min. at a high level by the addition of phosphate buffer.It is susceptible to changes in temperature, the Q10 between 16 and 36°C. being about 2. A tentative hypothesis is put forward that these electrical changes are caused by the spontaneous, reversible aggregation, or ‘turbulent wave formation’, which is characteristic of active and concentrated suspensions of ram spermatozoa; and that they are due to the position of the spermatozoa in the measuring apparatus rather than to any intrinsic changes in the electrical properties of individual spermatozoa. As the frequency and intensity of the wave formations are thought to be proportional to sperm motility, there is a possibility that the electrical changes might be used as an objective and physical measure of sperm motility. Certain advantages and disadvantages in measuring the activity of the sperm suspensions by this method are discussed.
The Toxic Action of Copper and Mercury Salts Both Separately and When Mixed on the Harpacticid Copepod, Nitocra Spinipes (Boeck)
Authors: Barnes H. , Stanbury F. A. 
Published: April 2021

ABSTRACT
The results are given of the poisoning of Nitocra spinipes (Boeck) by copper and mercury salts used together and separately. The state of copper and mercuric salts in sea water is examined using the available physico-chemical data. The results suggest that the two poisons act in a different manner and possible reasons for this are considered. The striking synergic effects obtained when the two metals are used together are considered to support the suggestion in 3 above and various possible explanations, both biological and chemical for this synergism, are examined.
Endocrine Activity During Insect Embryogenesis. Function of the Ventral Head Glands in Locust Embryos (Locustana Pardalina and Locusta Migratoria, Orthoptera)
Authors: Jones Bryn M. 
Published: April 2021

ABSTRACT
A brain-ventral head gland system operates in embryos of Locustana pardalina and Locusta migratoria. The initiation of growth and differentiation on the termination of diapause in the egg of pardalina takes place before the ventral head glands are formed. Maximal activity in the ventral head glands coincides with the retraction of the epidermis from the cuticle. Embryos, dissected out of the egg, were kept alive in aerated sterile Ringer’s solution for up to 2 weeks during which time they progressed in their development. If post-katatrepsis embryos are ligatured between the thorax and abdomen before a * critical ‘period the moult is limited to the thorax. If ligatured immediately behind the head, the body fails to moult. Since on the termination of diapause in the egg of pardalina mitosis begins before the formation of the ventral head glands, it is suggested that in locust embryos these glands are exclusively concerned with the retraction of the epidermis from the cuticle. It is suggested that the uptake of water by the egg of pardalina in stretching the cells stimulates a growth factor which, although present throughout the diapause phase, is only capable of initiating mitosis after the diapause phase has come to an end.
Hormonal Control of Ovary Development in Mosquitoes
Authors: Clements A. N. 
Published: April 2021

ABSTRACT
The control of ovary development by hormones has been shown in a number of insects, and evidence has been brought forward to demonstrate it in mosquitoes. It has been claimed on experimental grounds that a gonadotrophic hormone is secreted by the corpora allata after the intake of blood by female mosquitoes, co-ordinating ovary development with the supply of food (Detinova, 1945), and histological evidence has been produced connecting the corpora allata with ovary development (Mednikova, 1952).
Factors Controlling the Diurnal Rhythm of Activity of Periplaneta Americana L.
Authors: Harker Janet E. 
Published: April 2021

ABSTRACT
By using a direct method of recording activity the diurnal rhythm of activity of Periplaneta americana L. has been investigated in detail under various conditions of light and darkness. It has been found that there is no direct connexion between a hunger cycle and the activity rhythm. By means of experiments in which cockroaches were joined together in parabiosis it has been shown that a rhythm can be relayed from one insect to another, and is postulated that a secretion carried in either the blood or tissues is responsible for the transmission. Implantation of sub-oesophageal ganglia from cockroaches with a known rhythm into headless cockroaches has been found to result in the appearance of the known rhythm of activity in the latter. Effects of other endocrine organs on the activity rhythm has been investigated. The ocelli have been found to be directly connected with the establishment of the rhythm by the external factors of light and darkness. A rhythm of activity subsidiary to the main diurnal rhythm is described.
The Osmoregulatory Ability of the Lampern (Lampetra Fluviatilis L.) in Sea Water During the Course of Its Spawning Migration
Authors: Morris R. 
Published: April 2021

ABSTRACT
Although fresh-run lampems are able to withstand the effects of increasing sea-water concentration better than maturing animals, they can only maintain their plasma chloride constant in environments more dilute than 50 % sea water. This is achieved, in part, by gradually reducing the urine output from the normal fresh-water level (155-8 ml./kg./day) to a negligible rate in solutions which are mildly hypertonic to the blood (33 % sea water). Studies on the rate of change of weight loss, of plasma chloride and of plasma osmotic pressure following abrupt immersion in dilute sea water show that mature lampems cannot osmoregulate and can only survive in 33 % sea water by tolerating a raised blood osmotic pressure caused by water loss. Similar experiments on fresh-run animals suggest that the external surfaces of their bodies are less permeable to water than mature animals. Unlike mature animals, they also show considerable variation in the way in which they respond to 33 % sea water. Some are able to maintain their plasma osmotic pressure and chloride well below that of the environment. These animals also show little loss in weight, and this indicates that water is taken up actively, since this process has been shown to occur in some animals. Other fresh-run animals show raised plasma osmotic pressures in varying degrees and these are associated with larger losses of weight. These facts suggest that the hypotonic regulating mechanism gradually degenerates as the lampem enters fresh water.
Red Blood-Cell Antigens in Some Lower Vertebrates
Authors: Ashhurst Doreen E. 
Published: April 2021

ABSTRACTIt was not possible to find evidence for blood groups in frogs (one species) or in fish (three species). Frogs could not be induced to make antibodies after injection with red cells from another frog. Frogs, toads and tree frogs have a B antigen; newts probably have not.
Studies On the Respiration of Sea-Urchin Spermatozoa
Authors: Mohri Hideo 
Published: April 2021

ABSTRACT
Humphrey (1950) has established by microspectroscopic examination the existence of cytochrome spectra in oyster spermatozoa, and has further shown that cytochrome inhibitors such as cyanide and azide suppress the oxygen uptake of these spermatozoa. In sea-urchin spermatozoa, however, Barron, Nelson & Ardao (19486) have reported a contradictory result that, though the respiration is markedly depressed by cyanide, it is completely resistant to azide, even at high concentrations. On the other hand, Utida & Nanao (1954) have reported that the normal respiration of sea-urchin sperm is not affected by sodium azide, whereas the augmented respiration caused by 2,4-dinitrophenol (DNP) is completely abolished by this inhibitor. Since the presence of the cytochrome system in sperm cells has repeatedly been confirmed in a number of animals including sea urchins (Ball & Meyerhof, 1940; Zittle & Zitin, 1942; Mann, 1945; Rothschild, 1948), it is curious that azide fails to inhibit the normal respiration of sea-urchin spermatozoa.
Electricial Activity in A Slug Ganglion in Relation to the Concentration of Locke Solution
Authors: Hughes G. M. , Kerkut G. A. 
Published: April 2021

ABSTRACT
In studies of the activity of isolated organs it is desirable to bathe them in a fluid similar to that found in the intact animal. Previous work on nervous systems indicates that their electrical activity is greatly affected by the concentration of ions in the medium, except in cases where they are enclosed in a thick impermeable sheath. In gastropods the suitability of a 0·6-0·75 Locke solution for in vitro experiments on isolated organs was demonstrated by Cardot (1921), who studied the effect of different dilutions of mammalian Locke solution on the frequency and amplitude of the heart beat in Helix. A 0·7 dilution (sometimes called Cardot’s solution) has generally been used by previous workers on the nervous system of gastropods, and their preparations retained constant electrical activity for many hours, but there is an absence of studies on the effect of variations in the composition of the bathing fluid on the gastropod nervous system. This is of interest because the blood of slugs and snails is known to show considerable fluctuations in concentration. The problem may also be of significance in relation to the general behaviour of the animal, since it is known that these fluctuations are related to the activity of the animals.