LATTICE WORKERS, OR POLYCYSTINA. 99 



starch, and starchy products, elaborated by these 

 tenants (for they are not truly parasites), as well -as 

 their protoplasm and nucleus, are available, on their 

 death, for the nutrition of the Radiolaria which 

 harbour them. Nutrition, by means of other par- 

 ticles, obtained by the pseudopodia from the sur- 

 rounding medium, is by no means excluded ; indeed, 

 it is certain that numerous Radiolaria are nourished 

 for the most part, or wholly, by this means. Diatoms, 

 infusoria, as well as decaying particles of animal and 

 vegetable tissues, can be seized directly by the pseu- 

 dopodia, and conveyed, either to the surface of the 

 jelly-veil, or that of the central capsule, in order to 

 undergo digestion there. The indigestible constitu- 

 ents are collected, often in large numbers, and 

 removed by the streaming of the protoplasm. Pro- 

 fessor Haeckel seems to be firm in his opinion on 

 this point, for he alludes to those who have doubted 

 it, and then affirms : " I must, however, maintain 

 my former opinion, which I have only modified in 

 so much that I now regard the outer surface of the 

 jelly- veil (cafymma), rather than the outer surface of 

 the central capsule, as the principal seat of true 

 digestion and assimilation." 



Those bodies called " yellow cells/' which at one 

 time were a mystery, and afterwards declared to be 

 statoblasts, are now held to be yellow unicellular 

 algae, of the group Xanthellce, living within the sub- 



H 2 



