Morning journal and courier., 1883-03-21
The Mechanics' Course.

The Mechantcs' Course. The Agency ef Insects In the Fertfltza-
 tIon of FIOvvers-Lecture By pr. Jen-
 kfns.
 Dr. E. H. Jenkins delivered the last lecture ! of the course to mechanics before large ! and appreciative audience at North Sheffield Hall last evening on 'sThe Agency of Insects in the Fertilization of Flowers" from which we extract the following:
 Now in considering facts like these we say there is purpose in these arrangements; they have an object, design, and these terms are inteligible enough for our present purpose, which is not to discuss philosophy or theology. At the end of the last century, Christian Sprengel, in book entitled 'The Discovered Secret of Nature in the Structure and Fertilization of Flowers," wrote: 'sNa- ture seems to be opposed to the fertilization of any flower by it's own pollen" His care full observations had brought him thus far almost to the place where he could securely ground this theory to be somewhat modified of course by more extended observations. But he did not ground it securely and it dipped away out of sight and into forgetfulness for this reason. He did not show why nature should wish flowers to be cross-fertilized. Curiously enough only a few years later Andrew Knight, and after him Herbert and Gaertusr all recorded observations going to show that better fruit was obtained when flowers were cross fertilized than when self fertilized. Knight even goes so far as to say that no plant is self-fertilized through an un- limited number of generations. This Is the
 missing part which Sprengeps theory needed, but for long time no one thought to Drlng these two parts together and then to build upon them. It IS not improbable indeed that our knowledge has advanced more rapidly and surely In this direction because no lesser mind than that Of Darwin first recognized the connection be- tween the theory of Sprengel and that of Knight, and brought together and elaborated the whole in his Origin of Species by Means of Natural Selection, and subsequent pubiica tions
 The limit of time forbids any description of Darwin's own ingenious and remafKaD!y elaborate experiments on the effects Of sell and cross-fertiGzation, and we must content ourselves with the barest statement of his con clusions, which are these. In the great majority of plants both self and cross-fert1l1Zatlon
 take place. Cross-fertilization is generally
 beneficial self-fertilization generally lnJu- rious. In his experiments this was shown
 by the greater height, weight, cons1futlonai
 yipor and number of seed produced by cross
 fertilized plants as well as by the greater fer
 tility of their offspring.
 However, there are certain advantages in
 self fertilization. In some cases actually
 more seed is produced by it and so the per-
 petuation of the species is made more secure,
 for cross-fertilization is effected by external
 agencies and in case these fail the plant VIII
 be sterile unless it is self-fertile. We hnd
 then both methods of fertilization employed,
 some species in their present condition em-
 pIoying only one method, but most species
 constantly though not exclusively cross-ter-
 tilized.
 But the plant has no power of locomotion
 It cannot carry it's pollen to it's neighbors, nor
 can the pollen go of itself. Agencies exter-
 nal to it must transport the pollen, and the flower must provide means for securing tnls foreign aid. A comparatively small number of species are cross fertilized by the wind. in them, as rule, the pollen is very light, so that it will float in the air easily, 1t IS sneo great abundance because much of 1t will m evitably be lost, the Ailments are long and the pollen easily detached by the breezes, and the pistil is generally branched or hairy so as more readily to catch the pollen. The pines, ! poplars and grasses are examples of w1nd fertiiized or anemophllous plants.
 4 few ere cross -fertilized by the water. The vslIisneria for instance is dioecious- Hert I the DiEE1lLaL6 uOW6E IS 6CEu1 O4a 0 4OH6 SRAA ally tW isted thread feet long and floats or the surface of the water. The staminal howers are on very short stalks at the bot tom When ripe they break from thelI stalks and rising to the surface float about hither and thither, ,fertilizing the pistils when they come in contact. AS soon as tnAs female flower is fertilized, the spiral con tracts and draws it below to mature US seeo out of the reach of ducks
 A third agency in efecting cross -fertiiiza tion is birds, especially the humming bird Entering a flower in search of nectal their head or beak is dusteo with pollen, and part of this vii ! quite certainly he rubbed off on the pistll oi the next flower they enter, so securing the | desired cross.
 But in by far the larger number of cases 1 insects are the chosen carriers of pollen, ane ! we find that insects and flowers are to re markable degree mutually dependent ant mutually helpful. Most of the higher orderi | of insects, bees, wasps, ants and moths oe | pend wholly or in part on flowers for theil | food. The flower calls them by it's br1gh | colors and it's odor, sometimes captures holds them prisoners for time till its pollen is ready for distribution, pays fol | their services by supplying them with fooe | and then sends them away to its nelghbors
 carrying pollen with them.
 In the first place certain flowers offer tt | insects shelter from rain and wind or | nights lodging. For instance. some spee1e ! of the arum family to which our Jack In th' pulpit and skunk cabbage belong harbol | within their spathe sheltered from thu | weather multitudes of very small flies. On' 1 would think that the atmosphere and com pany in such place must be as delectable al | they are in a country corner grocery. Wher | it is abundant the harebell is said to be tn favorite refuge of bees when suddei
 shower comes up, or if they are beiated Il
 the evening they are in the habit of passinl the night in it. One of the poets speak of
 | ''FIowrets that dropping as day dropped too, | Fell into paYilions, white, purple and blue, | To shield the glow-woTm from the evening oe". The lecturer next treated of the means a the disposal of flowers for inducing insects t. ! visit them and for attaching their pollen t | them, the chief inducement being food | which is of two kinds, pollen and nectar
 The production of pollen and the secretion nectar was next explained. Color and per ! fume attract the insect visitor to tn l flower, which offers it food and perhap | shelter. The lecture further treated of tn | varieties of insects most active and useful II l the fertilization of flowers, and afforded oth CT interesting information, which was clearl. and forcibly presented.