March 15, 1895.] 



SCIENCE. 



291 



ous localization of germ-plasm in plants. 

 Weismann himself admits that the germ- 

 plasm must be distributed in ' minute frac- 

 tion ' in all ' somatic nuclei ' of the begonia 

 leaf, because that leaf is capable of giving 

 rise to new plants, by means of cuttings, 

 and all the plants may produce good 

 flowers, which, if they are sexual at all, are 

 so only by virtue of containing some of this 

 elusive germ-plasm. There is no other way 

 for these plants to get their germ-plasm, ex- 

 cept from the somatic leaf from which they 

 came. It would seem that this admission 

 undermines the whole theory of the local- 

 iziition of the germ-plasm in plants, for one 

 exception in the hypothesis must argue 

 that there are others. But not so ! There 

 are no insurmountable difficulties before 

 the Weismannians. It is the begonia which 

 is the exception, for it is abnormal for plants 

 to propagate by any such means ! The an- 

 swer which has been made to this state- 

 ment is that verj' many plants are jjropa- 

 gated asexually by horticulturists, and that 

 all plants can probably be so propagated if 

 there were any occasion for the eflbrt. 

 This answer is ti'ue ; but the philosophical 

 answer is that every phyton is an autonomj^ 

 and that the mere accident of its growing 

 on the plant, in the soil, or in a bottle of 

 water, is wholly aside from the point, for 

 wherever it grows it lives at first a sexless 

 life, it has an individuality, competes with 

 its fellows, varies to suit its needs, and is 

 capable, finally, of developing sex. 



Another fundamental tenet of "Weis- 

 mannism is the continuity of the germ- 

 plasm, the passing down from generation to 

 generation of a part or direct offspring of 

 the original germ-plasm. Now, if there is 

 any continuity in plants, this ancestral 

 gerin-j)lasm must be inextricably diffused in 

 the sonia-plasm, as I have said, for every 

 part or phyton of these plants, even to the 

 roots and parts of the leaves, is able to pro- 

 duce sexual parts or germ-plasm. And if 



this germ-plasm is inextinguishably associ- 

 ated with every cell of the plant bodj', why 

 does it not receive aud transmit all incident 

 impressions upon the plant ? Why should 

 acquired characters impress themselves 

 upon the soma-plasm and not upon the 

 germ-plasm when this latter element is 

 contained in the very nuclei, as Weismann 

 admits, of somatic cells? If the theory of 

 the continuity of the germ-plasm is true for 

 plants, then acquired characters must be 

 transmitted ! The only escape from this 

 position is an arbitrary assumption that one 

 plasm is impressionable and that the other 

 is not ; and, now, that we can no louger rel- 

 egate the germ-plasm to imaginary deep- 

 seated germ-cells, such an assumption is too 

 bold, I think, to be suggested. 



The entire Weismanuian hypothesis is 

 built upon the assumption that all perma- 

 nent or progressive variation is the result 

 of sexual union ; but I have shown that 

 there is much progressive variation in the 

 vegetable kingdom which is purely asexual, 

 and, for all we know, this type of modifica- 

 tion may proceed indefinitely. There is no 

 doubt of the facts ; and the only answer to 

 them which I can conceive the Weismanuian 

 to make is that these progressive variations 

 arise because of the latent influence of an- 

 cestral sexual unions. In reply to this I 

 should ask for proofs. Hosts of fungi have 

 no sex. I am not convinced but that there 

 may be strains or types of some species of 

 filamentous algte and other plants in which 

 there has never been sexual union, even 

 from the beginning. And I should bring, 

 in rebuttal, also, the result of direct obser- 

 vation and experiment to show that given 

 hereditable asexual variations are often the 

 direct result of climate, soil or other im- 

 pinging conditions. As a matter of fact, 

 we know that acquired characters may be 

 hereditary in plants : if the facts do not 

 agree with the hypothesis, so much the 

 worse for the hypothesis. Unfortuuately, 



