200 PROTOZOA 



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

 sporozoites. Multiplication without change of host (autoinfection) can 

 occur. 



21. The Gregarinida are temporary or permanent parasites in cells. 

 CoccidlcB, Htzmosporida (cause of malaria, parasitic in blood corpuscles). 



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

 lian muscles) and Myxosporida (psorosperm capsules of fishes, psorosperm 

 = spore) live in tissues or hollow organs. 



23. The CILIATA have numerous vibrating processes, the cilia, a 

 cuticle, and hence fixed openings for the ingestion of food (cytostome) 

 and for extrusion of indigestible matter (cytopyge). 



24. Of great interest is the occurrence of two kinds of nuclei, a func- 

 tional macronucleus and a sexual micronucleus. 



25. In conjugation portions of the micronucleus are exchanged and 

 accomplish impregnation. The macronucleus degenerates and is replaced 

 by part of the fecundated micronucleus. 



26. The classification of the Ciliata is based on the structure and 

 arrangement of the cilia. 



27. The Holotricha have similar cilia over the whole body. The 

 Heterotricha have, besides the total ciliation, stronger cilia in the neigh- 

 borhood of the mouth (adoral ciliary spiral). The Peritricha have only 

 adoral ciliation. The Hypotricha have the ciliary spiral and rows of 

 cilia and coalesced cilia on the ventral surface. The Suctoria have cilia 

 only in the young, later they become attached and feed through suctorial 

 tentacles. 



APPENDIX. 



According to the evolution theory one should expect forms between (he 

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

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

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

 a,re,Salinella salve, LohmaneUa catenula, the ORTHONECTIDA and the DICYEMIDA. 

 The Orthonectida and Dicyemida have a many-celled ectoderm, enclosing a solid 

 mass of cells in the Orthonectida, a single giant cell in the Dicyemida. Salwrlla 

 and Lohmanella consist of a single layer of cells enclosing a central digestive 

 space. Since the Dicyemida live as parasites in the nephridia of cephalopods, 

 the Orthonectida in worms and echinoderms, it is possible that their low organi- 

 zation is the result of degeneration. Trichoplax adhtrrens, formerly placed here, 

 is discoid, consisting of two epithelial layers separated by gelatinous tissue. 

 It has recently been shown to be the larva of a medusa, Eleutheria. 



