smallwood: maturation of haminea solitaria. 289 



astral figures, there are seen to be in the cytoplasm sun-ounding the 

 disintegrating wall of the old centrosome a number of rays and rows of 

 granules arranged radially to the old centrosome. In some instances 

 the granules are larger than those of the cytoplasm-; in others they are 

 of about the same size. Whatever may have been the origin of the rays 

 of the first maturation figure, their fate is unquestionable, since they 

 break up into granules which finally become indistinguishable. The 

 relation of the old and new astral rays to each other, and the relation of 

 the old rays to the sphere-substance, are well illustrated in the somewhat 

 unusual stage shown in Figure 58 (Plate 9), which is described beyond. 

 Ghromosomes. The earliest stage in the metamorphosis of the chromo- 

 somes, in the indirect process, is found in Figui'es 39 and 42 (Plate 7). 

 The conditions represented in Figure 39 are similar to those seen at this 

 stage in the direct process and in other animals generally. The chro- 

 mosomes have divided by a transverse division, and some of them have 

 begun to migrate toward their respective spindle poles. In Figure 42 

 there is to be noticed, besides the regular chromosomes lying in pairs, 

 an accessory chromosome that has already become enclosed by a vesicle 

 of its own, three sides of which are plainly discernible, as are also linin 

 fibres extending from the chromosome to the wall of the vesicle. In 

 Figure 38 the two masses of chromosomes have moved apart ; and around 

 the egg chromosomes a faint wall, connected with them by delicate linin 

 fibres, is visible. In this egg the nuclear vesicle evidently was com- 

 pletely formed before the chi'omosomes had changed much in position. 

 In Figure 43 each of the chromosomes has the form of a minute, thick- 

 walled vesicle, and is still free in the cytoplasm, no nuclear wall having 

 yet been formed around them. In Figure 40, on the contrary, the chro- 

 mosomes, though already vesicular, are enclosed in a common, well-formed 

 nuclear wall, the linin fibres have become distinct, and the chromosomes 

 are again assuming the solid condition, owing to a gradual thickening of 

 their walls. The chromosomes do not assume the form of large vesi- 

 cles which fuse to produce the wall of the nucleus, as in the telophase 

 of the second maturation figure, but retain their individuality during the 

 formation of the nuclear wall. The vacuolated condition of each chro- 

 mosome seems to be a phenomenon which is not necessarily associated 

 with the formation of a nuclear vesicle. The linin threads grow from the 

 chromosomes to the wall, and not vice versa, as is shown by the fact 

 that there are threads which are attached to the chromosome, but have 

 not reached the wall, whereas the converse of this was never found. It 

 is evident that considerable variation exists as to tiie time when the nu- 



