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SMALLWOOD : MATURATION OF HAMINEA SOLITARIA. 271 



the aster. It is certainly very evident in the later stages of Harainea 

 that the rays lengthen out toward the periphery, being at first short, and 

 that their length is correlated with the size of the spindle ; that is, that 

 they increase in length up to the metaphase. 



Chromosomes. Between the adult ovarian egg and the earliest matu- 

 ration stage discovered, profound morphological changes take place in the 

 chromatic matter, — changes which do not, however, occupy any consider- 

 able time ; for, as has been stated, an animal lays a whole capsule in the 

 course of forty-five minutes, the eggs always being in the metaphase when 

 laid. I have made repeated efforts to bridge over this gap in earlier matu- 

 ration, but without success. When one studies the germinative vesicle 

 of this stage (Plate 1, Fig. 4), he is impressed by the fact that it is a 

 very early stage in the formation of the achromatic figure. The paucity 

 of chromatic matter is at once evident. If any spireme has been formed, 

 it does not follow the usual course, nor does it appear to give origin to 

 chromosomes. In this early stage the germinative vesicle, already much 

 elongated, is filled with a loosely branched liuin network, which often 

 has at its nodes noticeable chromatin masses. There is to be seen in 

 connection with the linin one or more irregular vesicles, each containing 

 one or two chromatic masses. Because of the further changes that these 

 undergo, I have termed them chromosome vesicles {vsl. chr'so.). But 

 they are different in origin and function from structures iu the sperma- 

 togenesis of Brachystola magna similarly named by Sutton ( :00). It is 

 difficult to be certain just how these vesicles arise; ultimately sixteen 

 such vesicles are formed. I have been able to count thirteen vesicles in 

 one favorable section. At first these chromosomal vesicles are more or 

 less irregular in outline, but they soon assume an elliptical form (Plate 2, 

 Figs. 9-12). As the outline becomes more definite and regular, there 

 appears, on the inside of each, chromatin matter, which is usually dis- 

 tributed along the inner surface of the wall of the vesicle (Fig. 9). Soon 

 the chromatin begins to be concentrated, at first on one side of the vesicle 

 usually ; it then extends out toward the centre of the vesicle (Figs. 

 11-12). This chromatin mass is broadly connected with one side of the 

 vesicle, and a few delicate chromatin threads, or sometimes only one, 

 extend from it across the vesicle in various directions. These chromatin 

 threads are best seen in cross-sections of the spindle (Plate 3, Fig. 17). 

 They disappear as the chromatin increases in amount and definiteness of 

 form. The masses within the vesicles now begin to assume a form which 

 is very characteristic for Ilaminea, and we may speak of them from this 

 time on as the chromosomes. Each chromosome is more or less dis- 



