I40 C. M. CHILD. 



very faintly visible. It is possible that some method of fixation 

 which I have not employed may serve to render these phenomena 

 more clearly visible. In any case, however, it seems improbable 

 that the presence or absence of visible asters can be regarded as 

 of essential importance. 



It has not been possible to determine with certainty the num- 

 ber of chromosomes, though it is not far from eight, the most 

 frequent number in the spermatocytes. 1 The arrangement of the 

 chromosomes upon the spindle is very irregular and anything 

 approaching a typical equatorial plate is rarely seen. The chro- 

 mosomes exhibit the form characteristic of heterotypic divisions, 

 but no conclusions were possible regarding the direction of divi- 

 sion. Figs. 5 and 6 (PI. II.) show other examples of the first 

 maturation spindle. In Fig. 6 the extremely irregular passage 

 of the chromatic material to the two poles is shown. The chro- 

 mosomes often appear to be more or less broken up into chains 

 of granules, which seem in some cases to become wholly sepa- 

 rated from each other. It is impossible, of course, to determine 

 by observation whether the chromosomes maintain their individ- 

 uality during this process, but cases of this kind certainly do not 

 appear to strengthen the hypothesis of individuality. 



In some cases a nucleus with distinct membrane is formed after 

 the first maturation division (Fig. 7, PI. II.). In other cases, and 

 apparently more frequently, the second polar spindle appears 

 without an intervening resting stage (Fig. 8, PI. II.). 



The first polar body is of large size (Figs. 7 and 8, PI. II.) 

 and the centrosome is frequently visible beside the nucleus in it 

 (Fig. 8, PL II., Figs. 9 and 10, PI. III.). This centrosome stains 

 more deeply than in earlier stages and still later apparently un- 

 dergoes condensation to such an extent that it stains as deeply 

 with iron-haematoxylin as a mass of chromatin or a yolk granule. 



Fig. 8 (PI. II.) represents an early stage of the second matura- 

 tion spindle and Figs. 9 and 10 (PI. III.) later stages. Fig. 10 is 

 one of the very rare cases in which anything like a typical ana- 

 phase has been observed. The change in position of the spindle 

 during its development is apparent by comparison of Fig. 8 (PI. 

 II.) with Fig. 9 (PI. III.). 



1 Child, C. M., Biol. Bull., XII., 4, 1907. 



