120 



LUCERNARI^ AND TUEIR ALLIES. 



peduncle. Such is the simplicity of a coUetDcyst that we can scarcely add any- 

 tiiing that will characterize it better than as a " peculiar, granuliferous vesicle," 

 briefly mentioned in the original article above alluded to. Our figures, above enu- 

 merated, may assist considerably in forming a conception of its nature. It consists 

 of two kinds of materials, of which one is a perfectly homogeneous, transparent, 

 highly adhesive, and tractile semifiaid mass {fiijs. 97, 102, a"), which prevails to 

 the extreme limits of the cyst, and the other is a coarsely granular, colorless, semi- 

 transparent substance (a), which occupies the same area as the first, with the 

 exception of t\\e\x jieriiilieral stratum (a'). The latter, from its optical appearance, 

 would seem to have tbe character of a cell-wall, but that is hardly consistent with 

 its office as an adhesive body, nor with its faculty of being drawn out into con- 

 siderable extensions {fig. 102, «-). It is possible, though, that it is adherent and 

 plastic only on its exposed side ; since we may occasionally see two or three col- 

 letocysts {firj. 96) lying in contact, side by side, and yet with a sharp line of 

 demarcation between them. Tiiey vary considerable in size according to locality. 

 Those in the coUctocystophores {fi'js. 96, 97, o) have five or six times the diameter 

 of tliose of the digituli {fig. 101, o), and the latter are at least three times the size 

 of those most prevalent in the caudal adhesive disk {figs. 118, 120, a). 



