The Spermatogenesis of HYnRin Peas 529 



is an especial preparation for synapsis, the condition of the outer 

 one is surely paradoxical. 



Tile nucleus of the spore mother-cell enters into a complete 

 resting condition in which it remains during much or most of the 

 period of growth of the cell. As a preparation for synapsis the 

 chromatin of the recticulum collects into masses of irregular shape 

 and size, more or less arranged in threads, about the periphery of 

 the nuclear vacuole. The chromatin-thread at length takes up a 

 position around or closely applied to the nucleolus and the synap- 

 sis stage results. When the mass of chromatin unloosens, it is 

 seen to be made up of a much bent ribbon. The spireme is at first 

 beaded in appearance, but it becomes more regular in outline and 

 also increases in its capacity for absorbing stains. The splitting of 

 the .spireme was not clearly seen, although evidences of it were no- 

 ticed. In a few cells I saw the chromatin-loops which are char- 

 acteristic of the prophases of the first maturation mitosis (/. ij-ij), 

 but in each case the loop was not contracted and did not show 

 the second fission which was ob.served in the cotton hybrid. 



The two maturation divisions were quite like those seen in Ser- 

 pette and in Fillbasket x Debarbieux. The reduced number of 

 chromosomes was seven. 



A difference in the origin of the multipolar spindle of the first 

 mitosis of Express x Serpette from that of Fillbasket x Debar- 

 bieux was noted (this stage was not seen in Serpette), but whether 

 it was an artefact or not I was unable, because of the lack of ma- 

 terial, definitely to determine. In several spore mother-cells the 

 cytoplasm was very dense in the immediate neighborhood of the 

 nucleus, forming what was in effect a perinuclear zone. In these 

 cells the multipolar spindle .seemed to have its origin wholly within 

 the nucleus. The linin became lumpy and very distinct, it formed 

 a mesh-work which gave the appearance of polarity, and had every 

 indication of being the genesis of the multipolar spindle. The 

 nuclear wall remained in some cases recognizable even when the 

 intranuclear material was of a pronounced fibrous character. The 

 departure from the extranuclear origin of the spindle observed in 

 Fillbasket x Debarbieux is certainly a marked one, and interesting 

 even if it proves in the end to be an artefact. 



