550 P. W. WHITING 



But the only evidence that Lomen has for the cross-splitting is 

 a slight constriction and bending of the prophase chromosomes 

 in the middle. He states that Dr. W. Stempell, his professor, 

 is inclined to consider six as the normal number, and concludes 

 that therefore reduction must take place in the growth period. 

 This, however, is inconsistent with his account of spermatogonial 

 anaphases which, he states, show only three, and therefore reduc- 

 tion would be unnecessary. 



From what I have said in regard to the importance of em- 

 ploying the best technique, it will be evident, I think, that the 

 inconsistencies of the results of Taylor and Lomen are largely 

 due to imperfect technique. 



In a brief' paper on Corethra plumicornis, Dehorne ('14) con- 

 cludes that three is the diploid as well as the haploid number 

 of chromosomes in that species. Only one figure is shown, very 

 diagrammatic, of a somatic prophase. Dehorne speculates about 

 the possibility of parthenogenesis as an explanation of the reduced 

 number. It seems probable to me that here, also, the close 

 approximation of homologues is the true explanation of the con- 

 dition, and that a refinement of technique would reveal this. 



F. NUCLEOLI, HETEROCHROMOSOMES, AND CYTOPLASMIC BODIES 



a. Introductory 



The occurrence of condensed bodies in resting nuclei and of 

 darkly stained bodies in the cytoplasm has been the cause of 

 much confusion and speculation in the history of cytology. It 

 must be confessed that but little progress has been made in 

 regard to our knowledge of the cytoplasmic bodies. The nu- 

 cleoli, however, are somewhat better understood. In general 

 they bear a staining reaction reverse to the chromosomes. When 

 the chromosomes stain darkly the nucleoli are very diffuse or 

 absent (?). When the nucleoli come into prominence, the 

 chromosomes become diffuse or seem to disappear. For this 

 reason it has often been assumed that chromatic matter passed 

 from chromosomes to the nucleoli and the reverse. But there 

 is no more reason to suppose that this takes place than that 



