CRITICISMS AND CONCLUSIONS. 57 



body at one pole of a spindle, where a centrosome might be expected; 

 but he declines to regard it as such, because it is an isolated case. Lams 

 et Doorme (1907, p. 274) and Kirkham (1907k, p. 74) alone assert the 

 occasional presence of these structures, the former saying that there 

 are usually none with the first spindle. Lams et Doorme illustrate two 

 first spindles in side view, one in an egg from the ovary (fig. 2) and one 

 from the oviduct (fig. 5), the latter being the case to which Sobotta 

 calls attention as the exception to the rule that the first spindle is con- 

 fined to ovarian eggs. In the first case (fig. 2) they show no centrosomes, 

 but in the case of the egg from the oviduct (fig. 5) a curved rod occupies 

 one pole of the spindle. The latter, however, is probably a second spindle, 

 since the egg is in the oviduct and since all the second spindles figured 

 by them have somewhat similar centrosomes; furthermore, the chromo- 

 somes of this spindle resemble the chromosomes of the second spindle 

 rather than those of their fig. 2. As for the centrosomes drawn by Kirk- 

 ham, their presence is probably referable to the condition of the eggs, 

 many of which, as judged from an examination of his slides, were not 

 normal. It will be noted that some of his spindles do not show centro- 

 somes; they, we believe, are normal. There seems, then, to be no good 

 ground for the assertion that centrosomes exist in connection with the 

 first spindle. 



Sobotta (1 895, p. 44) states that the clear region around the chro- 

 mosomes of the spindle of eggs which produce only one polar cell has 

 almost precisely the extent of the vanished germinative vesicle. Since 

 this statement really relates to a spindle which does not originate from 

 the germinative vesicle directly (as Sobotta himself now admits), it 

 loses its significance. Lams et Doorme (1907, p. 274), who make a 

 similar assertion in connection with the first spindle, apparently have 

 not themselves seen the early stages (their fig. 3 being that of the second 

 spindle), and consequently have no other ground than Sobotta for their 

 assertion. According to our descriptions (pp. 26, 27, 33) this clear region 

 has no direct relation to the germinative vesicle. Since it exists, as the 

 circumpolar bodies also exist, during the periods of morphological 

 activity of the spindle, it also is probably a manifestation of such activity. 



Position and Orientation. 



Sobotta (1895, I 899. I 97) places much emphasis on the position 

 of the first spindle, which is situated deep in the egg. Our specimens 

 substantially corroborate his statement. Regarding the angle which the 

 axis of the spindle makes with the surface of the egg, there is some dis- 

 agreement among authors, arising, as it seems to us, from the paucity 

 of proper stages in the material which most of the investigators have 

 studied. It has been shown (p. 33) that the spindle may be parallel or 

 oblique to the surface, but that it is only rarely perpendicular at any 

 stage. Tafani (1889, p. 22) says that the spindle is from the first oblique, 

 not perpendicular, and figures it in an oblique position during the abstric- 



