MAUPAS'S RESEAECHES ON CILIATE INFUSORIANS. 613 



12. Probably the chromatic elements of the two pro- 

 nuclei retain their individuality in the copulation nucleus, 

 while only the nuclear accessories, their hyaloplasmas and 

 juices, undergo complete fusion. If this be so, fecundation 

 might be stated as the approximation of chromatic elements of 

 two distinct origins, and their incorporation into a single 

 nucleus. 



The above statements, No. 3 especially, require fuller explana- 

 tion. In the first place, while two mitoses are usually required 

 for the formation of the female pronucleus in Animals, three, at 

 least, are always requisite in the Ciliata; a point which Maupas 

 dismisses as " a special adaptation of the organism of these 

 Protozoa." His attempt to carry on this rule to the vegetable 

 world is very forced : it can, indeed, only be adopted for the 

 Archegoniata, where the successive formation of neck- and 

 belly-canal-cells compares very fairly with the formation of 

 polar globules in Animal ova; the first of which is known to 

 divide again in some Animals, like the neck-canal-cell of many 

 Archegoniates. But the identification with the processes in 

 the embryo-sac of Flowering Plants is only carried out by the 

 suggestion that all the authors who have described the evolution 

 of this structure are wrong in their description ! Maupas 

 admits that there is difficulty in finding similar mitoses, and 

 anything corresponding universally to " corpuscules de 

 rebut" in the evolution of spermatozoa, though some cases 

 present marked homologies. He also interprets the " vege- 

 tative nuclei " of the pollen as corpuscules de rebut, which 

 may be physiologically correct, but finds, at least in part, 

 another, morphological, explanation. He points out that all 

 authors are agreed in regarding the production of polar bodies 

 as involving the expulsion and elimination of a quantity of 

 nuclear substance useless for the normal evolution of the germ 

 cells ; but that Weismann's view as to the significance of this 

 elimination is disproved by the absolute identity of polar and 

 germ-nuclei in Metazoa ; and of the sister offspring of the 

 micronuclei in the Infusorian gametes. For the present 

 Maupas abstains in the chapter on a " General Theory of 



