254 C. O. WHITMAN. 



sponcTs so exactly with the appearance of the oral ring-disc in 

 Clepsine, on which the polar globules rest, that I feel warranted 

 in assuming, in the absence of proof to the contrary, that the 

 " clear spot " in Euaxes is homologous with the ring-disc of 

 Clepsine. If this be the case, then it is more than probable 

 that the globule which Kowalevsky supposed was produced by 

 the action of the acid, was one or both of the polar globules. 

 That this interpretation is correct is all the more probable from 

 the fact that the cleavage and embryo-formation in Euaxes are 

 strikingly similar to the same in Clepsine. 



2. Rhig-raijs. — So far as the ring-rays are concerned, very 

 little has been described, which offers more than a distant 

 analogy. The irregular stellate (" dendritisch — sternformig ") 

 figure seen by Brandt (^'po, Lymnaeus) may be better comj)ared 

 with the radial arrangement around one pole of an amphiaster 

 than with these ring-rays. Some of his figures of cleavage- 

 nuclei present a striking resemblance with the later stages of 

 the ring-discs. 



Some very interesting radial arrangements in the eggs of 

 spiders have been observed by H. Ludwig (4 H)* 



These columns of deutoplasm (" Deutoplasmasaulen") arrange 

 themselves in the form of a rosette around the cleavage-nucleus, 

 and therefore seem to bear a close relation to the nuclear ray- 

 systems. Kleineuberg (|^,) mentions peculiar ])seudopodial 

 processes of the yolk which accompany the early stages of 

 cleavage in Hydra. It is remarkable that these so-called pseu- 

 dopodes appear almost simnltajieousli/ with the cleavage, and 

 only on that pole of the e^^f^ where the cleavage depression first 

 appears. Why do they not accompany the cleavage in its 

 entire circuit ? I am inclined to believe that the *' folds " 

 observed by Metschnikoff (VV) ^^ ^^^ walls of the cleavage- 

 groove, in the egg of Si))honopliores (Epibulia aurantiaea) are 

 the same thing as the pseudopodes of the hydra-egg, only less 

 intensely expressed. 



3. FaUenkranz. — The same remark applies to the well-known 

 cleavage-folds (corona plicarum) of the amphibian t^)^, which 

 were discovered in 1824 by Prevost and Dumas, and afterwards 

 observed by Von Baer, Gotte, and others, and made a subject 

 of special study by Reichert and Max Schultze. Three explana- 

 tions of these fo'ds (FaUenkranz, lleichert) have been given. 



1. Reichcrt (--} <!-) in harmony with his theory that cleavage 

 is only a setting free of preformed cells, regarded them as 

 wrinkles produced in the closely adhering membranes of cells in 

 ])rocess of separating. " Das Entstehen des Ealtenkranzcs is 

 nur dadurch zu erkliiren, dass die beidcn ersten, eng an einander 

 gepressten und fest adhiirirenden Furchungskugeln bereils vor 



