26 



PROTOZOA 



Reproduction. — {a) Binary fission. The nucleus divides first, 

 then the central capsule, then the extra-capsular tissue, {b) Spore- 

 formation. The intra-capsular protoplasm divides into small 



^' Egested particle 



Nucleus 



Con f roc tl/e vacuole 



Fig. 4. Actinosphaerium, a Heliozoan. (Drawn by H. N. Lammers. After Leidy.) 



masses, each of which becomes a flagellula with a single flagellum. 

 Sometimes the spores produced are alike, in others they are di- 

 morphic some being microspores and others megaspores. 



Symbiosis of Radiolaria. — Radio- 

 laria and algae (yellow cells) live in 

 symbiotic relation. (See page 482.) 

 The radiolarian supplies CO2 and N 

 waste. The alga gives off O and 

 makes sugar. 



P arasitic S arcodina. — Lambl 

 (i860) discovered an organism in 

 feces of a child and decided that it 

 was connected with diarrhea, but 

 later rejected this opinion. Later 

 (Afte7calkTns757o%;;'7/irPro- Lewis and Cunningham (1870) found 

 tozoa. Courtesy of Lea and amebae in the feces of nearly 20 per 

 Febiger.) cent of cholera patients examined in 



India. They were not the cause of 

 cholera, however. Other investigators found two species of ameba 

 in the intestine of man, one harmless, Entameba coli^ one causing 

 dysentery^ Entameba histolytica (Fig. 5). 



E-ndosome —- 



Cor lex of 



chromalin 



Fig. 5. Endamoeba intestinalis. 



