l62 



Scientific Proceedings (39). 



chromosomes in these parthenogenetic eggs is due to the omission 

 of a synapsis period, and not due to a separation of the chromo- 

 somes subsequent to synapsis. Synapsis appears, therefore, to be 

 a phenomenon associated with the union of the paired chromo- 

 somes and to have no other significance for development. 



Two years ago I reported that two classes of spermatozoa are 

 formed in phylloxerans, as in other insects, but that the male- 

 producing class degenerates. Consequently all the fertilized eggs 

 have the female number of chromosomes. I reported that, never- 

 theless, when males appear in the later life cycle, they have a 

 smaller number of chromosomes (one or two less) than the par- 

 thenogenetic female or the sexual female. I suggested that one 

 (or two) chromosomes must be lost in the polar body of the male 

 egg. I can now state that this inference is correct, since I have 

 found all stages in the separation of the daughter plates in the 

 polar spindle of the male egg. In the telophase one double chro- 

 mosome (its halves equal) is found lagging in the middle of the 

 spindle. It passes always to the outer pole, which means that the 

 lagging chromosome passes to a prescribed pole. The theoretical 

 questions involved will be discussed elsewhere. The lagging chro- 

 mosome lies outside of the nucleus of the polar body, sometimes 

 in a vesicle of its own. In the female egg all of the chromosomes 

 divide equally in the polar spindle and no lagging body is present. 



I04 (5M) 



The biological significance of the Sertoli cells. 



By F. M. HANES. (By invitation.) 



[From the Department of Pathology, College of Physicians and 

 Surgeons, Columbia University.] 



In the normal testicle there are three parenchymatous elements, 

 namely, sperm-forming cells, Sertoli cells and interstitial cells. 

 In the cryptorchid testicle only two types of cells are found, 

 Sertoli cells and interstitial cells. The latter form the bulk of 

 the cryptorchid testicle; the former line, in a synchtial manner, 

 the small seminiferous tubules. 



Since the genitalia of castrated animals are very atrophic and 

 secondary sexual characters absent, while both are normally de- 



