148
ABSTRACTS
for the desired period. The
following staining
methods have given him excellent results.
(a) Tungstic haematoxylin method
It consists of mordanting the film in a 2 per cent
solution of phosphotungstic acid in distilled water for
not less than 10 minutes. This period may be extend-
ed to several hours. Shorter period is said to be
adequate for amoebae while the longer are better for
cysts or flagellates. The film is next thoroughly
washed in distilled water and stained for 10 minutes
or longer (15-30 minutes or even several hours) in 0.2
per cent solution of "ripened" haematoxylin. Cysts
and flagellates require a longer time for staining.
After staining, wash in distilled water and then
transfer to tap-water where it may be kept for 15 to
30 minutes (the water may be changed 2 or 3 times).
The film appears purple to the naked eye and is ready
for dehydration with alcohol, and is ultimately mount-
ed in balsam or damar in the usual way.
(b) Molybdic haematoxylin method
This method is exactly like the foregoing, except
that a 2 per cent. solution of ammonium molybdate is
employed as a mordant in place of phosphotungstic
acid. The author has obtained equally good prepara-
tions of Giardia, Entromonas, Embadomonas, etc., with
both methods of staining.
Advantages of these
methods are that they are rapid and easy, and do not
involve the process of differentiation under the micro-
scope, as is customary with ordinary iron—haematoxylin
method. [H. N. R.]
The storage of artificially dried grass, Wright
Normanc (1942). J. Agric. Sci. 31, 194-212.
THE paper deals with the effects of humidity and
moisture content—the two generally recognized im-
portant storage deterioration factors—on the keeping
quality of artificially dried grass. Certain drawbacks
in the drying processes and storage are pointed out.
Preliminary experiments over humidity ranges of
40 to 100 per cent revealed a close parallelism between
humidity and moisture content. Detailed experiments
based on the above findings under accurately controlled
conditions revealed an extremely high moisture con-
tent of dried grass in atmospheres of high humidity:
thus at 80 per cent humidity the moisture content
was 18 per cent, at 90 it was 28 per cent and at 100
per cent humidity it was 50 per cent. Differences in
composition did not materially affect the humidity-
moisture content relation.
Tentative observations spread over 18 months on
the level of humidity and moisture content favouring
deterioration revealed that the critical humidity for
mould growth lay between 67 to 80 per cent. Extended
observation over these ranges shew (a) that the mould
growth was a definite function of relative humidity
i.e., in three days at 100 per cent relative humidity;
five days at 90 per cent; 50 days at 75 per cent and in
300 days at 70 per cent humidity, (b) a contradiction of
the usual assumption that if mould growth did not
occur in two to three weeks, the product was immune
from deterioration, emphasizing the need for a pro-
longed study, (c) that mould growth may take place
even at 70 per cent relative humidity if stored for a
long time.
Experiments designed to detect mould growth at an
earlier stage by plating methods rather than by
direct mycelial detection under the microscope proved
unsuccessful.
The rate of increase in mould growth
was dependent upon moisture content and humidity
and for reasonably safe storage, a relative humidity
of 67 per cent corresponding to a moisture content of
13 per cent was recommended, though this does not
confer absolute immunity from mould growth. At a
given moisture content, mycelium formation was as a
rule seen to precede the development of musty smell
while the latter inturn was capable of being detected
long before a significant rise in plate count could be
made out; as such, the first two were considered to
be the earliest and most reliable indications of mould
growth.
Caution was indicated in recommending
limits of moisture content for long period storage, as.
this is dependent upon the mould microflora, hygros-
copic nature of sample and local changes in moisture
content and therefore in the surrounding air humidity
of the sample. [K. G. R.]
Cystic pituitary in young cattle with vitamin A
deficiency. L. L. MADSET, S. R. HALL and
H. T. CONVERSE (1942). J. Nutr. 24, 4.
DURING their studies on the gonadotropic and lacto-
genic hormones of the anterior lobe of the pituitary,
the authors examined more than 10,000 pituitaries
from apparently normal cattle and observed that only
four or five glands in the whole group were definitely
cystic. In contrast to the above observation, in a
planned experiment with .young cattle which developed
varying degrees of vitamin A deficiency, these authors
could demonstrate a large occurrence of cystic pituitary
gland. For the purpose of the experiment two groups
of animals were chosen, one consisted of beef animals
of shorthorn and shorthorn-hereford cross, the other
group belonged to dairy Jersey and Holsteins.
Amongst the beef animals two were depleted of
vitamin A by continuously feeding a deficient ration
for sometime. On autopsy, the pituitary glands of
both were found cystic. In one of these animals,
which was on a vitamin deficient diet early in life but
later fed adequate amounts of carotene, no evidence of
repair in the cystic pituitary was found. Apparently
the injury to the gland brought about by vitamin A
deficiency at the early part of life was permanent.
The other beef calves were from cows receiving 30 to
45 Ug. of carotene per kilogram of body
weight.
Symptoms of vitamin A deficiency were evident in these
calves at birth. All of them except one had cystic
pituitaries.
The dairy animals examined in this study were all
born to cows receiving sufficient carotene for normal
reproduction. Soon after their birth, these animals
were kept on rations of varying degrees of vitamin A
deficiency.
In due course, all the animals developed
symptoms of deficiency. Two of the animals receiv-
ing the least carotene had very large pituitary cysts.
Two others receiving apparently adequate amount of
carotene developed cystic pituitary when carotene
supplement was discontinued or partially withdrawn.
In two other animals while the symptoms of vitamin
deficiency were marked, the cyst in the pituitary of
one was not large and histologically no evidence of
injury to the glandular parenchyma was seen, while in
the other the autopsy revealed an apparently normal
pituitary.
The cyst in the pituitary of the vitamin A deficient
animals occurred either in the residual lumen or within
the posterior lobe, often causing compression of the
gland and injury to the glandular parenchyma. Ac-
cording to the authors, the injury to the pituitary
gland in calves under vitamin A deficiency was pro-
bably due to the results of the mechanism responsible
for injury to both optic nerve tracts and other part
of the central nervous system. [S. K. T.]
GIPD—S13ICofAR—25-1-45—550.