1877 ] 173 IMcCrady. 



4. That the result of this conjugation is twofold. 



(A) A result of the combination of the nucleus of the spermato- 

 zoon with the germinative vesicle of the ovum ; which result is the 

 future animal. And 



(B) The aggregation of the yolk-protoplasm, yolk-masses and 

 granules with the protoplasm of the spermatozoa, all these together 

 constituting a store of food for the immediate nourishment of the 

 newly arisen animal. 



5 . That the newly found animal (A) is in all essential respects 

 a Rhizopodal or Amoeboid being, which at once proceeds under 

 proper life-conditions to appropriate as food the provision (B) thus 

 furnished it; and effects this in a manner essentially Rhizopodal; 

 i. e., by prolongations of its own substance enclosing in manifold 

 ways, and part by part in smaller and smaller successive portions 

 differing but little in size, the whole provision (B). 



6. This appropriation of the whole provision (B) is the process 

 called segmentation, and the equivalent processes seen for example 

 in the eggs of insects and the higher Crustacea. It is not necessary 

 that it should be always a distinct segmentation, either total or par- 

 tial, but it is necessary that it should be, under this theory, in all 

 cases, a Rhizopod-like procedure. 



7. In the conjugation, the weight of testimony from various ob- 

 servers, makes it probable that the germinative vesicle and the sper- 

 matozoon (or its nucleus) disappear and cease to exist as such. In 

 their stead arises the new animal, or protembryo. 



8. This may present itself under one of three forms. 



a. A clear mass of protoplasm within the yolk mass — the embry- 

 onal vesicle of Wagner. Entoprot embryo. 



b. A uniform, or nearly uniform layer of protoplasm, completely 

 inclosing the yolk mass. Ectoprotembryo. 



c. A combination of a and b — that is, the coexistence of a clear 

 nuclear mass of protoplasm at the centre, with a distinct peripheral 

 layer of protoplasm, the two being connected together by radial 

 threads of protoplasm. Pantoprotembryo. 



9. In the first case, a, the protembryo is supposed under this the- 

 ory to appropriate the yolk by radial prolongations or pseudopodia 

 extending themselves centrifugally towards the surface of the yolk. 



In the second, b, the same end is assumed to be attained by the 

 extension inwards of centripetal prolongations. 



