86 TOILERS IN THE SEA. 



rudiment of the shell, or other mineral framework, of 

 the organism is secreted. In the Foraminifera and the 

 Polycystina they are the nidus within which (in the 

 Foraminifera) the primordial calcareous chamber of 

 the shell is secreted, or (in the Polycystina) the 

 earliest siliceous rudiment of the siliceous framework, 

 or perforated shell." 



The " sarcoblast " is in reality a small sphaeroidai 

 mass of sarcode, generally varying in size, in the 

 different families, within certain limits, and wholly 

 devoid of any true membranous or other special 

 covering. When first observable, it consists of an 

 almost colourless, hyaline, viscid, and basal fluid, of 

 the consistence and appearance of the white of an 

 egg, within which are distributed peripherally, but 

 without any approach to regularity, a number of 

 granules of more consolidated, as well as more or less 

 faintly coloured sarcodic substance, and invariably 

 (in the case of the sarcode of the oceanic Rhizopods) 

 of a tolerably brilliant yellow tint. But, by carefully 

 focussing down to an equatorial plane, a central por- 

 tion, altogether devoid of granules, and occupied 

 solely by the pure basal sarcode, may quite readily 

 be detected. It is to this clear portion that the some- 

 what misleading name of nucleus has been applied ; 

 perhaps owing to the idea that its apparently higher 

 refractive power, as compared with the surrounding 

 mass, may be due to its being a specialised product, 



