303 



Spermatogenesis of Caloptenus femur-rubrum ' ). 



Preliminary notice. 

 By E. V. Wilcox, Mus. Comp. Zool., Cambridge, Mass., U. S. A. 



The testicular follicles of the Caloptenus femur-rubrum 

 are long blind tubes. The spermatogonia are found at the blind end 

 of the tubes. Then follow in succession the zone of the prophases of 

 the first division of the spermatocytes, the zone of the two maturation 

 divisions and that of the metamorphosis of the spermatids. 



The chromatic rings and "Vierergruppen" described by vom Rath, 

 Haecker and others are easily demonstrated in Caloptenus. In the 

 early prophases of the first maturation division is to be seen a coiled 

 thread with chromatic granules scattered along its entire length. This 

 thread breaks up into twelve segments which become associated in 

 pairs in such a way as ultimately to form rings. The segments come 

 to lie parallel to each other and the free ends of each pair are then 

 united thus forming closed figures or rings. At the time of the first 

 maturation division there are consequently six chromatic rings. 



Each ring becomes a "Vierergruppe", either from the moment of 

 its formation or later, by the concentration of the chromatic substance 

 into four bodies, chromosomes. In some cases the chromatin in the 

 original segments becomes concentrated into two bodies, one at either 

 end of the segment. When two such segments unite with each other by 

 their free ends, the' resultant ring contains already four chromosomes. 

 But the rings may be formed while the chromatin is still distributed as 

 small granules along the whole thread; in that case the four chromo- 

 somes arise in the ring by a subsequent concentration of the chromatin. 



The two maturation divisions which follow result in giving each 

 spermatid six chromosomes. One of the elements of each "Vierer- 

 gruppe" is inherited by each of the four spermatids which result 

 from the two spermatocyte divisions. 



According to my observations on Caloptenus, therefore, both 

 maturation divisions are reduction divisions in Weismann's sense. 

 For there is in my material no longitudinal splitting of the chromatic 



1) Contributions from the Zoological Laboratory of the Museum of 

 Comparative Zoology at Harvard College, under the direction of E. L. 

 Makk, No. XLIV. 



Note. The paper of which this is an abstract was finished and presen- 

 ted for publication May 16, 1894. A temporary interruption in the publi- 

 cation of the "Contributions" has prevented its prompt appearance and 

 1 have therefore requested the author to write out a brief statement of 

 his conclusions as a preliminary communication. £. L. Mabe. 



