56 



THE CELL 



than the most minute micro-organism. As to its composition, it 

 appears to consist of the same substance as the so-called neck or 

 middle portion of the seminal thread, to which, further, during' 

 the process of fertilisation, genetic functions have been ascribed 

 {vide Chap. VII., 1). When the ordinary methods for staining 

 the nucleus are employed it does not absorb any of the dye ; 

 if, however, special reagents, especially acid aniline dyes, such as 

 acid fuchsine, safranin, and orange, are used, it becomes vividly 

 coloured. This is the only way to distinguish the central cor- 

 puscle from the other granules in the cell (microsomes) unless it 

 is enclosed by a special radiation sphere or envelope. If we dis- 

 regard the processes of cell division and of fertilisation, which are 

 treated of in later sections, the central corpuscles have been, up 

 till now, most frequently observed in lymph cells (Flemming II. 

 11, 12 6, and Heidenhain II. 16), in the pigment cells of the 

 Pike (Solger II. 38), and in the flattened epithelial, endothelial, 

 a,nd connective tissue cells of Salamander larvce (Flemming II. 

 12 6). 



As a rule there is only one central corpuscle present in each 

 lymph cell (Fig. 34) ; this can be seen without having been 



stained, since the protoplasm in its im- 

 mediate neighbourhood assumes a distinctly 

 ray-like appearance forming the radiation, 

 or attraction sphere, which later on will 

 occupy so much of our attention. The cen- 

 tral corpuscle is sometimes situated in an 

 indentation of the nucleus, or, if the latter 

 has broken down into several pieces, a con- 

 dition which is frequently seen in lymph 

 cells, it lies between them and some portion 

 or other of the protoplasmic body. 



In pigment cells (Fig. 35), Solger (II. 38) 

 was able to make out the radiation sphere 

 as a bright spot between the pigment gran- 

 ules, and in consequence he concluded that 

 the central corpuscle was present. 



In the epithelium of the lung, and in the 

 endothelium and connective tissue cells of 

 the peritoneum of Salamander larvce (Fig. 

 36 A, J)), Flemming found, almost without 

 exception, that instead of a single central 



Fig. 34. Leucocyte 

 from the peritoneum of a 

 Salamander larva. For 

 the sake of clearness in 

 the figure, the central cor- 

 puscle, surrounded by its 

 radiation sphere, has been 

 distinguished by a bright 

 rinsr, which is not really 

 present in nature. (After 

 Flemming, Fig. 5.) 



