35 



the pseudopodia ; and (3) the vacuolated portion between 

 called the " calymma " which is concerned with flotation. 



The inner (intracapsular) endoplasm is encased by a 

 perforated " central capsule," and thus separated from 

 the outer (extracapsular) mass or ectoplasm, which is 

 often supported by an additional skeletal framework of 

 silica or by loose radiating spicules. The flinty skeletons are 

 often of exquisite construction; and the accumulated remains 

 form the well-known " Radiolarian Ooze " of the deep sea. 



Peculiar " yellow cells" (zooxanthellce and zoochlorellce) 

 are found in most Radiolarians (in the "calymma"), and 

 the association appears to be that of symbiosis. 



Binary fission occurs in the forms that have not 

 complex skeletons ; but the more frequent mode of re- 

 production is by formation of flagellated swarm-spores. 

 An example is Thalassicolla, which is found floating in 

 swarms in the warmer seas. 



Write a Note descriptive of the Skeleton in Radiolarians. 



The Radiolarian test or skeleton is frequently a double 

 formation consisting of an inner chitinous central capsule 

 and an outer skeleton of silica or of acanthin or strontium 

 sulphate, either in the form of a lattice framework or a 

 loosely woven arrangement of spicules. It exhibits diver- 

 sity of form and is often very complex. By the union of 

 a number of skeletal rods in various ways or by the modi- 

 fication of a single skeletal ring or tetrad, a stellate, spherical, 

 or helmet-shaped openwork case may be formed ; and 

 these cases are often multiple, one inside another. 



The chief function of the skeleton is hydrostatic, it 

 serves as a support for holding out the outer ectoplasm ; 

 for instance, the twenty radial spines of Acanthometra 

 serve like so many tent-poles upon which the vacuolated 

 ectoplasm is hoisted and held stretched out. 



Explain the Association between Zooxanthellce (" yellow 

 cells ") and Radiolarians , and show in what ways 

 it is advantageous to both. 

 The ZOOXANTHELL.E are pelagic like the Radiolarians. 



The stores of nitrogenous waste in the mucilaginous bodies 



