no SCIENCE PROGRESS. 



The demonstration, remarkably complete when the 

 conditions of work are considered, follows. It ap- 

 pears to me, though it may be a reactionary view to 

 take, that for morphologists, who professedly make a 

 study oi form, the doctrine that "parts which are hidden 

 because of their infinite smallness, and gradually emerge 

 from it, are fables," is an extremely wholesome one. I 

 do not wish to be misunderstood in this matter. The 

 various "gemmules," " plastidules," "micellae," " inotag- 

 mata," "plasms," " biophors," the whole company of 

 assumed existences demanded for the theoretical expla- 

 nation of observed facts, has been no doubt extremely 

 useful in its proper place, and has done much to stimu- 

 late inquiry and give precision and definite direction to 

 research. But we should remember always that they 

 are, one and all of them, fabulce ; they are not sensible 

 existences, and they have not even the value of the 

 analogous assumptions, atoms and molecules, because, 

 unlike these last, they cannot be made serviceable for 

 calculations, they cannot be put to the test of a rigorous 

 logical method. There is a time and a place for all 

 things, for scientific speculation and for statement of 

 scientific fact ; it seems to me that speculation is out of 

 place when the existences which it assumes are incorporated 

 into statements of fact, and when the course of events 

 which it has pictured is held to have overthrown a 

 doctrine so firmly and satisfactorily founded on fact as 

 that of epigenesis. 



I am not raising a ghost for the purpose of laying it. 

 Weismann, who began by seeking for an epigenetic 

 theory of development, has altogether given up the 

 attempt in his last work, and he states frankly that he is 

 an exponent of an evolutionary doctrine. Thus, "Spencer's 

 theory is epigenetic, Darwin's evolutionary ; in this re- 

 spect the latter is, in my opinion, superior to the former V 



1 The Germ Plasm, a theory of Heredity by August Weismann, 

 translated by W. Newton Parker and Harriet Ronnfeldt. London : W. 

 Scott, Limited, 1893, P- 5- 



