84 
THE ORGANIC CELL 
but later observations made by Riickert and others have clearly 
proved the truth of his theory. 
Riickert and Hacker have shown, that in Cyclops , the 
paternal and maternal chromosomes remain separated during 
the anaphase, and also give rise to double nuclei in the two- 
cell stage. Herla and Zoja show that if the variety of 
Independence of Paternal and Maternal Chromatin in the 
Segmenting Eggs of Cyclops. 
A. First cleavage figure, complete independence of paternal and maternal 
chromosomes. B. Resulting two-cell stage with double nuclei. C. Second 
cleavage ; chromosomes still in double groups. D. Blastomeres with double 
nuclei from the eight-cell stage. (A-C. from Riickert, D from Hacker.) 
Ascaris having two chromosomes ( bivalens ) be fertilised with a 
spermatozoon of the variety univalens having one chromosome, 
the three chromosomes appear at each successive cleavage, 
and the paternal chromosome, from its smaller size, can be 
distinguished from the two maternal ones at each division. 
