i8o NATURAL SCIENCE. mav. 



ceivable, for he says : — " It must be admitted that there are cases, 

 such as the cHniatic varieties of certain buttertiies, which raise some 

 difficulties against this explanation. I myself experimentally investi- 

 gated one such case, and even now 1 cannot explain the facts 

 otherwise than by supposing the passive acquisition of characters 

 produced by the direct influence of climate " (p. 99). 



The next and last point is the machinery required for transmitting 

 the effects of the environment, presumably produced at the periphery 

 of the organism, to the germ-cells. When, however, we remember 

 that protoplasmic continuity is probably maintained through all 

 nucleated cells in conjunction, that the threads unite the nuclei into a 

 community, and that the cell-walls themselves are, so to say, 

 saturated with living protoplasm, too; and if germ-plasm accompany 

 this universally distributed protoplasm, we seem to have the very 

 machinery required for the purpose. Thus can we hypothetically 

 account for the fact that flowers with germ-cells can be produced from 

 any part of the vegetative system, and that any specific characters, 

 such as roots, bulbs, and tubers, may be produced abnormally on the 

 aerial parts of plants ; and, lastly, that the power of reproducing any 

 acquired characters may be transmitted to the germ-cells, and 

 consequently such may be then hereditary. 



If the theory, as represented in Dr. Weismann's work, is thus 

 shown to be insufficient to account for hereditary traits of plants, as 

 seen in the vegetative system, there remain the reproductive organs 

 which constitute the flower. 



As these, and these alone, contain germ-cells, it would seem that 

 they are the only organs which one would suppose, a priori, capable of 

 being influenced by the direct action of the environment. The 

 application of the theory to The Origin of Floral Structures through 

 Insect and other Agencies, is, therefore, apposite. '■♦ 



Dr. Weismann observes with regard to the localisation of germ- 

 cells : — " The whole individual is composed of the millions of somatic 

 cells by which the reproductive cell is surrounded" (p. 75), and 

 again, " the number of somatic cells becomes so large tliat they 

 surround the reproductive cells with many layers " (p. 77). 



This description does not apply to plants. The egg-cell of the 

 embryo-sac, and the sperm-cell of the pollen-grain are close to the 

 surface. Thus light can penetrate to the ovule and turn it green, 

 and one layer of cells only separates the pollen from the atmosphere. 



In my work just quoted I endeavoured to show that the infinite 

 variety of adaptations to insects discoverable in flowers may have 

 resulted through the direct action of the insects themselves, coupled 

 with the responsive power of protoplasm. I cannot verify the 

 deduction experimentally, for it is impossible to make a flower, 



1' This is the contention of my work with the above title. Iiitoiuit. Sci. Series, 

 vol. Ixiv. 



