354 ELEMENTARY BIOLOGY. [CHAP. 



(Sect. 5. d. ft) ; one or more of these may be con- 

 nected with an individual cell. They arise as out- 

 growths of the constricted cell-base, the whole fre- 

 quently having the appearance of an inverted T with 

 a thick stem (cell-body) and greatly elongated arms 

 (the fibres). 



b. The cells of the interstitial tissue (cf. Sect. 5. e. ft) much 

 smaller than a, and often separable from one another 

 only with difficulty. Numbers of them will be found 

 to contain two nuclei (evidence of active division). 



c. The nematocysts ; highly refractive bodies to be found 

 in both a and b in the latter in abundance and in 

 all stages of development. Look for the under- 

 mentioned (cf. Sect. 3). 



a. The larger nematocysts ; each consists of a body, 

 ovoidal and truncated, with a strongly-marked 

 double contour due to the thickness of its wall ; a 

 neck, inverted and^ beset by three or four powerful 

 spines ; a filament, lying within the base of the 

 body, coiled into a spiral the edges of which may 

 occasionally be seen (cf. Sect. 3). 



Compare a large nematocyst in the everted state ; 

 the summit of the neck is beset by a series of ex- 

 cessively delicate spines. 



ft. The smaller nematocysts; rarely present in the larger 

 cells. Each is ovoidal and much smaller than a, 

 having a similar double contour. The filament ; 

 but i to jV the length of, and very much stouter 

 than, that of a; at rest looped, in eversion fre- 

 quently spiral (cf. Sect. 3). 



