396 MONTGOMERY. [Voi.. XIII. 



shoe shape, as found by Burger ('90b, Fig. 61 b, c). Usually 

 a coarse-grained peripheral layer of chromatin {Chr.) is pres- 

 ent, each of these larger grains being apparently composed of 

 finer microsomes ; and centrally, fine-grained chromatin is 

 distributed in the nuclear sap. In only a few nuclei were evi- 

 dences of a delicate achromatic reticulation to be found. Occa- 

 sionally the chromatic granules are limited entirely to the 

 periphery, the central portion of the nucleus containing only 

 nuclear sap ; on the other hand, sometimes the whole nucleus 

 appears to be nearly filled with chromatin. The different ways 

 in which the chromatin may be distributed probably correspond 

 to different physiological states of the nucleus, and cannot be 

 considered artifacts, since the same differences are found after 

 the use of various reagents. 



Each nucleus contains one large spherical nucleolus («), 

 which is usually centrally placed, rarely peripherally, and never 

 in close contact with the nuclear membrane ; this latter position 

 is typical for the nucleoli of cells IV. A layer of chromatin 

 granules usually surrounds the nucleolus, and from this layer 

 fibres radiate towards the peripheral masses of chromatin. Not 

 infrequently two nucleoli are present, which are then usually of 

 different size and placed at varying distances from each other ; 

 but in only one case did I find the two nucleoli stained differ- 

 ently (Fig. 22 b). I never found more than two nucleoli, and 

 never saw evidences of nuclear division, though I had paid par- 

 ticular attention to these points. 



Burger states ('90b, p. 1 13) : " Bei I habe ich immer mehrere 

 [nucleoli] beobachtet," which shows that he had confounded 

 chromatin masses with nucleoli. By the term micleoliis I 

 understand, in accord with most cytologists, a body contained 

 within the nucleus, usually of a spherical form, which stains 

 intensely with eosin (after the use of the double stain, 

 haematoxylin -\- eosin). It should not be confused with the 

 irregular masses of chromatin, which stain with haematoxylin, 

 and each of which is composed of finer microsomes. Burger 

 has also described for C. marginatiis and Langia slightly 

 staining, but little refractive ("von mattem Glanz ") globules 

 (Blaschen) continued within the nucleus. Thus ('90b, p. 113) : 



