TiiaUty and' Organizaiion of Protoplasm. 77 



in the non-nucleated blastomere without tlie presence, and therefore 

 without the aid of any nuclear or chromatic substance. ^ 



All these manifold and numerous observations and experiments go to 

 prove that the non-nuclear plasm is the real l)earer of the vital activi- 

 ties and potentialities. '^ 



Conclusions drawn from appearances found in fixed and tinted spec- 

 imens, however instructive, are apt to lead investigators to interpret 

 flowing vital phenemena morphologically and mechanically, instead of 

 looking upon them as specific chemical processes, of which the changing 

 morphological appearances are incidental, though definitely disposed, 

 perceptible expressions. Of course, it is from these visible appearances 

 that we have to infer what is really happening. But we have to be 

 careful to regard them simply as mass-manifestations of a process at 

 work among the intimate, ultra-visible constituents of the vitally chang- 

 ing substance. The entire organism, in all its living parts, down to 

 the very core, is in constant vftal commotion, and repres.ents essentially 

 a synthetic chemicaLlaboratory in ceaseless activity. It is not, as has 

 been long believed, essentially a mechanical apparatus, whose wheel- 

 work is made to run by the burning of food-material. 



This caution of not mistaking morphological appearances for stable 

 machine-like structures, or for static chemical compounds, has to be 

 especially borne in mind in interpreting the process of mitotic division, 

 and above all that of fertilization and its accompanying morphological 

 appearances. Here it is safe again to rely in great measure on what 

 can be so readily and so clearly observed in the self -division of suitable 

 Infusoria, the purport of which is likewise the ontogenetic evolution or 

 reproduction of new individuals. I have in a general way described the 

 morphological signs of the exceedingly complex chemical activity at 

 work during the comparatively elementary case of reproduction taking 

 place in Colpoda. In the reproduction of highly complex organisms we 

 have to expect, even in parthenogenetic, and all the jnore in bisexual re- 

 production, correspondingly complex manifestations of the ontogenetic 

 process. But here also reproduction of the adult organism can start only 

 from germs, which are specific chemical fragments of the organism from 

 which they are derived, and which they are destined to reproduce. This, 

 I think, has been sufficiently proved, and seems indeed quite obvious. 



Now as regards what really happens during fertilization in Metazoa, 

 starting with fully matured male and female germ-plasm, and leaving 

 out of consideration the preceding .phenomena of their maturation, I 

 believe that Boveri's observations and views, supplemented by those of 

 Wilson, and confirmed by a great number of investigators, as applying 

 to many kinds of animals ; that these views can be taken as a solid founda- 

 tion for the understanding of what really occurs during fertilization. 



After the matured spermatozoon has entered the matured egg, we 

 know for certain that the egg-plasm itself has a definitely organized, 

 bilateral structure; and we know that it is the medial, non-nuclear por- 

 tion of the spermatozoon which is the active agent in fertilization. We 



