PROGENITOES OF MAN. 279 



'proof of the earlier existence of this most ancient ancestral 

 stage, based upon the fundamental law of biogeny, is pos- 

 sibly still furnished by the circumstance that, according 

 to the assertions of many investigators, in the beginning 

 of the development of the egg, the cell-kernel, or nucleus, 

 disappears, and the egg-cell thus relapses to the lower stage 

 of the cytod (Monerula, p. 124 ; relapse of the nucleated 

 plastid iato a non-nucleated condition). The assumption 

 of this first stage is necessary for most important general 

 reasons. 



Second Stage : Amoebae. 



The second ancestral stage of Man, as of all the higher 

 animals and plants, is formed by a simple cell, that is, a little 

 piece of protoplasm enclosing a kernel. There still exist 

 large numbers of similar " single-celled organisms." Among 

 them the common, simple Amoebae (vol. i. p. 188, Fig. 2) 

 cannot have been essentially different from these progenitors. 

 The form value of every Amoeba is essentially the same as 

 that still possessed by the egg of Man, and by the egg of 

 all other animals. (Vol. i. p. 189, Fig. 3.) The naked egg- 

 cells of Sponges, which creep about exactly like Amoebae, 

 cannot be distinguished from them. The egg-cell of Man, 

 which like that of most other animals is surrounded by a 

 membrane, resembles an enclosed Amoeba. The first single- 

 celled animals of this kind arose out of Monera by the 

 differentiation of the inner kernel and the external proto- 

 plasm ; they lived in the earlier Primordial period. An 

 irrefutable proof that such single-celled primaeval animals 

 really existed as the direct ancestors of Man, is furnished 

 according to the fundamental law of biogeny (vol. i. p. 309) 



