THE NUCLEI OF UROLEPTUS MOBILIS 315 



be inferred that division of. the chromosomes is transverse. The 

 evidence for this, however, is by no means convincing and the 

 plane of chromosome division, for the present at least, must remain 

 an open question. 



In later anaphase stages, these daughter chromosomes become 

 drawn out into loose and irregular lines of chromatin granules 

 (figs. 41 and 42) and in the telophase stage a definite chromatin 

 reticulum is present (figs. 43 and 44). After division, this chro- 

 matin reticulum resolves itself into homogeneous granules of the 

 vesicular nucleus characteristic of the prophase of the second 

 maturation division. 



The absence of uniformity in these first maturation spindles 

 is peculiar and difficult to interpret. If both types were found 

 in the same individual we might conclude that the first and more 

 indefinite type is characteristic of nuclei destined to take no 

 further part in the maturation processes. Unfortunately, each 

 conjugant contains only one type and, since almost all ex-con- 

 jugants continue to live after conjugation (of sixty isolated ex-con- 

 jugants all but seven continued to live and to divide), one type 

 appears to be as potent as the other. 



Not only is there a difference in the first maturation spindles, 

 but there is also a difference in the prophases or parachute stages. 

 I have been unable, however, to correlate these different and rela- 

 tively rare types of prophase with either of the two types of 

 maturation spindles. In the second type of prophase, the gran- 

 ule forming the first pole of the spindle is accompanied by ap- 

 proximately one-half of the total chromatin content of the mi- 

 .cronucleus (figs. 49 to 53). I have not found spindles that can 

 be interpreted as arising from these aberrant parachutes, and, 

 from the number of micronuclei in individuals containing them, 

 I regard them as nuclei undergoing degeneration. 



b. The second maturation division and reduction of chromosomes. 

 There are from four to eight products of the first maturation 

 division, most of which undergo granular disintegration and dis- 

 appear. Tw^o or sometimes three of them take part in the second 

 maturation division, but I have not seen any individual with 

 more than three, while the great majority of pairs in this stage 



