THE NUCLEI OF UROLEPTUS MOBILIS 



317 



chromosomes which appear in the ensuing third division, but, 

 notwithstanding an abundance of material obtained in this stage 

 of conjugation, I am unable to decide how the chromosomes actu- 

 ally divide. The minute size of the spindles and the close 

 packing of the chromosomes are conditions which render direct 

 observation uncertain and encourage any tendency which the 



Fig. 47 First maturation spindles, first type, four in one individual, three in 

 the other. X 800. 



observer may have to infer an interpretation along the hues of 

 preconceived ideas of what the process should be. I will try 

 to avoid the latter pitfall by describing some actual spindles as 

 they appear under the highest lens system at my command. 



The most conspicuous and the most frequent stage is illustrated 

 in figure 55, a. In this stage the chromosomes are densely 

 stained and appear as rods occupying the two central quarters 



