Katharine Foot aud E. C. StrobcU 205 



this area is unmistakably assuming the form characteristic of spindle 

 fibers. Photos. 81, 82, 83, 84 and 86, Plate Y, indicate with equal 

 clearness that the cytoplasm contributes to the polar rays. These 

 photographs (84 and 86) suggest a very close if not causal relation be- 

 tween centriole and spindle and may be called in evidence to support the 

 theory that the spindle is formed under the influence of the centrioles. 

 In these preparations the chromosomes certainly do not influence the 

 form of the spindle, for although they are all massed on one side, 

 yet the spindle remains symmetrical in relation to the centrioles. 

 Even if this massing of the chromosomes in one-half of the spindle is 

 not the normal condition it should produce an abnormal and distorted 

 spindle, if the rays were formed only in relation to the chromosomes. 

 "We are forced to conclude, therefore, that the spindle is a life expression 

 of the nucleoplasm and jjolar cytoplasm, or is formed under the in- 

 fluence of the centrioles. 



Nucleolus. — In a comprehensive history of the nucleolus, Montgomery, 

 '98, shows what a bewildering number of conflicting interpretations have 

 accumulated around this structure since it was first figured by Fontana, 

 in 1781, and what little progress has been made in solving the problems 

 of its significance, even its morphology being enveloped in a mass of con- 

 tradictory evidence. We hope to be able to establish the morphology of 

 the nucleolus of the egg of AHolohophora foetida by a careful compara- 

 tive study of its form after killing in a variety of fixatives, by a study of 

 the living egg, and of the dried germinal vesicles, as obtained by the 

 method described on p. 200, We are convinced that its variety in form 

 can be best appreciated when demonstrated by a number of photo- 

 graphs and with sufficient data for each fixative it may be possible to 

 arrive at a correct decision between the artificial and the normal struc- 

 tures. 



The germinal vesicle of AHolohophora in common with many other 

 forms contains two distinct kinds of nucleolar formations, and for these 

 we shall adopt Flemming's term, principal and accessory nucleoli. The 

 former is the relatively large nucleolus which has persisted and increased 

 in size since its first appearance in the smallest oocyte of the ovary 

 and is peculiarly the nucleolus of the oocyte first order. The accessory 

 nucleoli are first seen in the large ovarian eggs, and the earliest stage at 

 which we find them they are very small and in close proximity to the 

 chromatin (Photos. 9, 11, Plate I, 23, Plate II, and 49, Plate III), and 

 after many fixatives stain like the chromatin. The two structures, the 

 principal nucleolus and the accessory nucleolus, differ in several respects, 

 as a rule only one of the former is present in a germinal vesicle (Photos. 

 15 



