THE RELATION BETWEEN AMITOSIS AND MITOSIS. 93 



no visible cell membrane is present. For the sake of simplicity, 

 however, the approximate area of the cytoplasm about the nucleus 

 is indicated by a line. 



To give a detailed description of the development of the repro- 

 ductive organs in Monicsia is beyond the present purpose. The 

 morphological features concern us only secondarily and will be 

 considered only so far as may be necessary for the understanding 

 of other matters. 



II. THE NUCLEUS AND THE TYPES OF DIVISION. 



The nuclei of most of the somatic structures and of the young 

 germ cells do not differ widely in appearance. The nucleus con- 

 tains a deeply staining " nucleolus " which appears to be at least 

 in large part chromatic in composition and might perhaps more 

 properly be called a karyosome. For the present, however, I 

 prefer to use the term nucleolus. After the usual degree of 

 extraction this is very commonly the only element stained in the 

 nucleus which appears entirely homogenous except for this body. 

 With less extraction other granules are visible scattered here and 

 there through the nucleus, but a distinct reticular structure does 

 not appear. This type of nucleus is shown in most of the figures 

 of earlier stages of ovarian development. In various figures there 

 are cases where the nucleus shows a few small granules in addi- 

 tion to the nucleolus (Figs. 8,A,&,d, e, etc., 13, C, etc.). Nuclei 

 are frequently found with two nucleoli both of which may be of 

 equal size (Figs. 8, A,/ ; 14, A, a, etc.) or they maybe unequal 

 (Figs. 14, D ; 15, />, a; 16, b, etc.). The question as to 

 whether the two nucleoli always arise by the division of one it 

 has been impossible to settle. Sometimes (Fig. 15, A, a) a 

 minute nucleolus is found apparently in contact with a much 

 larger one and occasionally (Figs. 7, c ; 9, B] two nucleoli ap- 

 parently connected by a strand of stained substance are seen. 

 On the other hand, in many cases the two nucleoli of very differ- 

 ent size are widely separated (Fig. 8, A, a and g] as if one were 

 arising de novo. It seems impossible to decide such questions 

 as this until our methods of study of the cell are greatly im- 

 proved. From my own observations I should conclude pro- 

 visionally that both methods of origin exist. It is certain, how- 



