Introduction to Animal Morphology. 6i 



group are large yellow cells found imbedded in the 

 sarcode, each included in a colourless membrane : 

 these yellow cells are short-lived, and multiply by 

 fission or endogenously. Their nuclei are sometimes 

 red, and often resist the action of caustic alkali, as 

 if encapsulated. Their number is variable, and not 

 constant in any species ; but they are rarely absent 

 except in some Acanthometridae. As they have been 

 seen living and multiplying when the rest of the body 

 was dead, Cicnkozvsky conjectured that they may be 

 parasitic, but they are too constant to be so. 



Radiolaria are found either floating on, or at the 

 bottom of, the ocean, and they multiply by swarm- 

 spores or germs, developed from the contents of the 

 central capsule. Miillcr saw the inside of an Acan- 

 thometra full of monadiform vesicles, which became 

 actinophrys-like. Hacckel noticed the capsule-con- 

 tents of Sphaerozoum breaking up into vesicles, and 

 saw some of these vibrating. Schneider saw amoeboid 

 vesicles with movable flagella in Thalassicolla. The 

 formation of these swarm-spores was minutely traced 

 in Collosphsera (which has a fenestrated shell) by 

 Cicnkozvsky ; here the contents of the capsules break 

 into little spheroids, which become monadiform, bici- 

 liated, and pass through the holes in the shell, each 

 spore with a crystalline rod, and a few oil globules 

 within. Young Radiolarians have no central capsule, 

 thus showing their relations to Heliozoa. The shells 

 of Radiolaria are abundant in some Tertiary deposits : 

 those from Barbadoes earth are well-known as 

 Polycystina. They existed as far back as the days of 

 the Carboniferous formation, if the genus Traquairia 

 be a true Radiolarian. 



