Il8 THE ANIMAL PARASITES OF MAN 



(20) EECKE, J. VAN. Sarcosporidien (Geneesk. Tijdsch. v. Nederl.-Indie, 1892, 



xxxii. ; Jaarsverl. Labor, path. An. en Bact. te Weltevreden [1892], Batavia, 



1893)- 



(21) PIANA, G. P. Fasi evolut. d. Sarcosp. (La clinica veter. 1896, p. 145. C. f. B., 



P. u. I. [i], xx., p. 39). 



(22) LAVERAN and MESNIL. Morph. d. Sarcosp. (C. R. soc. biol. 1899 [10], vi., p. 245), 



APPENDIX TO THE SPOROZOA. 



After bacteriology had, through R. Koch, attained unforeseen import- 

 ance, the living agents of a number of the so-called infectious diseases of man 

 and domestic animals were discovered, but the participation of living organisms 

 in the causation of other diseases as well as neoplasms was denied. The 

 character of these disturbances, however, led investigators to conjecture that 

 living organisms were also to blame for their causation, and to search 

 for them. Although investigations were instituted by various persons, it 

 cannot be denied that the entire question was first brought forward by the 

 works of L. Pfeiffer in Weimar. Starting with the search for the specific 

 agent of smallpox, this author with untiring zeal pursued the study of the 

 parasitical protozoa, and his publications, independent of many discoveries for 

 which science is indebted to him, aroused much interest, and inspired, directly 

 and indirectly, that impetus which has led to so many important discoveries. 

 Of course many hopes and expectations have remained" unfulfilled, although 

 they appeared to be justified, and the investigations, especially directed 

 to the discovery of the agents of malignant neoplasms, have as yet had 

 no favourable results and are still a matter of dispute. Now, as formerly, 

 the opinions of parties are strongly opposed to each other, that which appears 

 to one person to be Blastomycetes or Myxomycetes, others declare to be 

 Sporozoa or other primitive animals, whereas still others declare that the 

 same formations are the degeneration products of cells. 



However necessary a knowledge of the works and opinions of his 

 predecessors may be to the investigator of this difficult subject, the less 

 it appears, under the present circumstances, to be necessary to enter here 

 on to debated ground. It is to be hoped, however, that the time is not far 

 distant that will yield suitable methods for the attainment of more certain 

 results. 



Class IV. Infusoria. 



The bilaterally symmetrical body of the infusoria is enveloped 

 in a cuticle which has numerous openings for the passage of the 

 cilia. Most kinds have a fixed shape, whilst changes in the form 

 of others are brought about by the contractions of the body sub- 

 stance. The latter exhibits the hyaline ECTOSARC, in which 

 contains numerous vacuoles. The CILIA, the various arrangement 

 MYOPHANES and occasionally also TRICHOCYSTS (minute spindle- 

 shaped bodies) appear, and the granular ENTOSAR'C which frequently 

 of which supplies the principle on which this class is divided, are 

 always processes of the ectosarc ; their form varies ; they may be 



