NUCLEOLI. 119 



are, however, not peculiar to inflammation, but appear in the colos- 

 trum and in the egg. They are regarded as free nuclei, and are 

 represented by Fig. 59. 



Fig. 59. 



2 





Glomeruli and granular cells. The dark cells are the glomeruli. 1. From inflamed lung. 2. From 

 inflamed pia mater. 3. From tubercular meningitis. 



5. The nucleolus is a round, sharply defined, fat-like granule, 

 generally of a dark color, and measuring T2 J^^j to g^^ of an inch 1 

 in diameter. It is inferred that they are vesicular, from their 

 sharply defined form, from their similarity to free nuclei, and from 

 the fact that, when large, a cavity filled with fluid frequently be- 

 comes developed in them. Acetic acid does not dissolve them. 



They are believed to be constituted of fat, with an albuminous 

 compound for the investing membrane. 



Nucleoli are generally found in nuclei while still young, and in 

 many during their whole existence. Still, they cannot be regarded 

 as an essential constituent of the cell, like the nucleus, since they 

 cannot always be with certainty recognized in the latter. Cells 

 without nuclei, of course, have no nucleoli. 



Usually but one nucleolus is found in a nucleus, but frequently 

 there are two; and in solitary cases four or five may be found, 

 which then are either eccentric, or lie free in the nucleus. 



A nucleolus is, therefore, histologically, an undeveloped nucleus ; 

 and since both nucleoli and nuclei contain fat, and the free granules 

 in cells consist of it usually, in part at least, fat is always indis- 

 pensable in the plasma from which cells are developed. On the 

 other hand, there is no evidence that fibrine exists in the cell- wall 

 or the contained fluid. All agree that the former is an albuminous 

 substance. 



That fibrine, therefore, is the only plastic element in the blood, is 

 highly improbable. The remark of Gluge, that " the formation of 

 fibres and cells from fibrine is a matter of direct observation," 2 



1 In ganglion-cells, and in the germinal spots of ova, they sometimes measure 



*uW to TlW of an inch ' 



2 Pathological Histology, p. 50. 



