SUPERNUMERARY CHROMOSOMES IN CEUTHOPHELUS. 223 



maturation mitosis, shows that they are univalent. In Diabrotica 

 soror I have considerable evidence that the supernumeraries owe 

 their origin to a transverse and a longitudinal division of X 

 ('12 . tii'l it seems probable that those of Ccnthophilus have had 

 -'milar origin. I have occasionally found ca-e- where A" 

 "ied about to divide late in the first maturation mitosis 

 I md 20), but I have as yet no evidence of a tran-\ < 



di\ i-ion. 



SYNAPSIS. 



The. material which was collected in K)ii with the hope of 

 at on the origin of the Bupernumerari< \ed 



to be l'.i\orable for a study of synapsis, or, as I -hould prefer to 

 call the phenomenon, conjugation of the chronio-onu -. T! 



' - uere all fixed in Flemming and stained with either thionin 

 or iron-haematoxylin. Thionin gave the clearest figures. 



In the re-ting nuclei of the spermatogonia the chromo-ome- 

 are eii her \ i-iblr as separate individuals as in Fig. 21, or are m >re 

 (.1 1 upleiely resolved into rather fine spireme thread- a- 



in I -. In sonic follicles one sees only such -pennatogonial 



nuclei .1- in Fig. 21; in others the various cyst- -h\\ \arimis 

 Dilution into spireme threads. The former condi- 

 tion I should attribute to more rapid division of the -permato- 

 '^onia, the time between mitoses being insufficient for complete 

 H -olntion. 



In the \oimgcst spermatocytes, distinguished from the -p.-rma- 

 >nia by the condensed condition of A', the -pin -me thread- 

 are -i milar to those of the spermatogonia, per hap- a lit tie coarser. 

 They are finely granular and more or less nodular. There is no 

 contra, tion, or synizesis, stage and no complete pol.iri/atioii of 

 loop- to form a perfect bouquet stage. The -pirem- threads are 

 n-uallv irregularly but rather evenly distributed through the 

 nucleus as in I ig. 2.}, which also shows A' in characteristic position 

 a-ain-t the nuclear membrane. Fig. 2.\ -ho\\ - an extreme and 



1 i j. Spermatogonial nuclei, slmwiMi; 1 mm --..Ivr. I . liro- 



1 i.. . ; Spcrmatocyte nucleus before syna; 



l-'ii.. .'i Similar stage showing partial pnlari/.iticn \ rhr<>i: 



I i. 16. Stages in parasynapsi-. 



