ON THE LIFE-HISTORY OF THE FORAMINIFERA. 131 



stained and unstained regions, variously distributed, may be 

 detected. In sections of specimens stained with picro-carmine, 

 and afterwards with methylene blue, they retain the red stain, 

 while the surrounding protoplasm is stained blue. 



They are at least as frequently met with, and in that 

 case they are as abundant, in young individuals as in old ones. 



In a batch of specimens of Polystomella collected in October, 

 and kept in dishes of sea-water for some months, these bodies 

 are found, after the usual preparation, to be almost entirely 

 absent. The water in which the Polystomellas were kept 

 contained numbers of Infusoria, and some small clumps of 

 brown algae, which may have served as food. Although the 

 protoplasmic contents of the shell may have shrunk during the 

 period that they were submitted to these conditions, and their 

 nuclei, as will be shown later, underwent a very marked diminu- 

 tion in size, few or none of the specimens died. Out of 116 

 examples only four showed any indication of the bodies under 

 consideration. Some of the specimens were killed in January 

 (after three months' captivity), and the remainder in March 

 (after five months) ; and, with the second set, examples freshly 

 collected from the sea were killed and stained, using the same 

 solutions for all. In those fresh from the sea the stained spheres 

 were more abundant, though fewer than in specimens collected 

 in summer. 



How are these bodies to be regarded ? 



It appears probable that they are either of nuclear nature, 

 or that they are food material in some stage of metabolism. 



In favour of their nuclear nature is the fact that with the 

 reagents which I have used they have the same staining re- 

 actions as the nuclear elements. 



On the other hand against their nuclear nature many con- 

 siderations may be urged. 



They are generally (at least in four cases out of five) absent 

 altogether from specimens in which the large nuclear elements 

 are well stained, and their presence or absence appears to be 

 "entirely independent of any change which may be seen in these 

 nuclei. They may occur in both microspheric and megalo- 



