116 



SIMPLE HISTOLOGICAL ELEMENTS. 



vision or by endogenous development. (KolliTcer, p. 12.) Thus they 

 incline towards merely inorganic forms, as produced by crystal- 

 lization. 



It should be added that in some cells no granules exist, but only 

 a clear fluid, as in case of the fat-cells and the colored blood-cor- 

 puscles. 



4. The nucleus is a globular or lenticular body, measuring from 

 etnjzj to 5o J ou f an inch- 1 It is attached to, or imbedded in, the 

 wall of the cell, except in case of the free nuclei already mentioned, 

 which have escaped from the parent cell, and have no nucleoli ; and 

 is transparent and of a yellowish color. All nuclei are themselves 

 vesicles. The contents are, besides a nucleolus usually present, 

 almost invariably a yellowish or transparent fluid; and in this both 

 water and acetic acid precipitate the same dark granules which are 

 found floating in the cells. 



Acetic acid, however, renders the nucleus more visible, while it 

 dissolves the cell-wall. But the pus-corpuscle, which Grluge incor- 

 rectly regards as a mere nucleus, is dissolved by this acid. 



Sometimes this vesicle (the nucleus) contains formed grannies, 

 .as the spermatic filaments (spermatozoids) in semen (Fig. 54), and 

 peculiar granules (germinal spots) in ova (Fig. 55). The germinal 

 spot is actually a nucleolus within the germinal vesicle, the latter 

 being the nucleus of the ovum. 



.Fig. 54. 



Spermatozoids. 1 to 4. Their variety 

 in form. 5. Seminal granules. 



Germinal spot, &c.,of ovum. 1. Stroma of the ovary. 2aud 

 3. External and internal tunics of the Graafian vesicle. 4. 

 Cavity of the latter. 5. Thick tunic of the ovum, or yolk-sac. 

 6. The yolk. 7. The germinal vesicle. 8. The germinal spot. 



1 It sometimes measures even from 

 and ova. 



to 



of an inch, as in ganglion-cells 



