PROTOZOA. 



22. In conjugation portions of the micronucleus are exchanged 

 and accomplish impregnation. The macronucleus degenerates and 

 is replaced by part of the fecundated micronucleus. 



22. The classification of the Ciliata is based on the structure 

 and arrangement of the cilia. 



23. The Holotriclia have similar cilia over the whole bod}^ 

 The Heterotricha have besides the total ciliation stronger cilia in 

 the neighborhood of the mouth (adoral ciliary spiral). The Peri- 

 triclia have only adoral ciliation. The Hypotriclia have, on the 

 ventral surface, the ciliary spiral and rows of cilia and coalesced 

 cilia. The Suctoria have cilia only in the young, later they 

 become attached and feed through suctorial tentacles. 



24. SPOKOZOA are parasitic Protozoa, usually without organs 

 of locomotion or mouth. They take no solid food, but live by 

 osmosis on tissue fluids. In reproduction the encysted animals 

 produce spores (apparently always beginning with fecundation and 

 accompanied by a change of host). The spores divide again into 

 sporozoites. Besides, multiplication without change of host (auto- 

 infection) can occur. 



25. The Gregarinida are temporary or permanent parasites in 

 cells. (Spores = pseudonavicellae, sporozoite = falciform embryo). 

 Coccidite, Hcemosporida (cause of malaria, parasitic in blood 

 corpuscles). 



26. The Sarcosporida (Rainey's -or Miescher's corpuscles of 

 mammalian muscles) and Myxosporida (psorosperm capsules of 

 fishes, psorosperm spore) live in tissues or hollow organs. 



APPENDIX. 



According to the evolution theory one should expect forms between the 

 Protozoa and Metazoa. The CATALLACTA spheres of ciliated cells which in 

 reproduction break up into single cells have been described as such. 



FlQ. 160. Section of half of Trichoplax adhcerens. (After Schulze.) 



Peculiar many-celled animals whose position in the system is difficult to 

 decide are, further, Trichoplax adhcerens, Salinella salve, the ORTHO- 

 NECTIDA and the DICYEMIDA. Trichoplax (fig. 160) is discoid and consists 

 of twoepithelial-like cell layers separated by gelatinous tissue. The Ortho- 



