

DERIVATION OF PARASITES 23 



vented a return into the intestines, where the eggs could be 

 deposited. Most of them doubtless died off, as parasites at 

 present, as also their young stages do when they penetrate wrong 

 hosts. A part of them, nevertheless, passively reached the intes- 

 tine of beasts of prey. Many were -destroyed in the process of 

 mastication ; for a small part, however, there was the chance of 

 reaching the intestine of a beast of prey undamaged, and there, 

 having become larger and more capable of resistance, maturity 

 was attained. By means of this incidental coincidence of various 

 favourable circumstances, these processes, according to Moniez, 

 have been established by heredity and have become normal. 



This is not the place to express an opinion either for or 

 against the various hypotheses advanced, but the existence of 

 these diametrically opposed views will alone show the great diffi- 

 culty of the question. Independently, however, it appears more 

 natural to come to the conclusion that parasitism as well as 

 change of hosts were gradual transitions. 



As a conclusion to this introductory chapter, I append a list 

 of the most important works on the helminthology of man and 

 animals. 



LITERATURE. 



GOEZE, J. A. E. Versuch einer Naturgeschichte der Eingeweidewurmer thierischer 



Korper. Blankenburg, 1782. 4to, 471 pp., with 44 plates. 

 ZEDER, J. G. H. Erster Nachtrag zur Naturgeschichte der Eingeweidewurmer, von 



J. A. E. Goeze. Leipzig, 1800. 4to, with 6 tables. 

 RUDOLPHI, C. A. Entozoorum sive vermium intestinalium historia naturalis. I., 



Amstelod., 1808 ; ii., 1809. 8vo, with 18 plates. 



RUDOLPHI, C. A. Entozoorum synopsis. Berol., 1819. 8vo, with 3 plates. 

 BREMSER, J. G. Ueber lebende Wiirmer im lebenden Menschen. Wien, 1819. 8vo, 



with 4 plates. 

 BREMSER, J. G. Icones helminthum, systema Rudolphii entozoologicum illustrantes. 



Viennae, 1824. Fol. (Paris, 1837). 

 DUJARDIN, F. Histoire naturelle des helminthes ou vers intestinaux. Paris, 1845. 



8vo^ with 1 2 plates. 

 DIESING, C. M. Systema helminthum. 2 vols. Vindobonae, 1850, 1851. 8vo. 



Supplements by the same author : Revision der Myzhelminthen (Report of 



the Session of the Imp. Acad. of Science. Wien., xxxii., 1858) ; with addendum 



(ibid., xxxv., 1859) ; Revision der Cephalocotyleen (ibid., xlix., 1864, and xlviii., 



1864); Revision der Nematoden (ibid., xlii., 1861); Supplements (ibid., xliii., 



1862). 

 BENEDEN, P. J., van. Memoire sur les Vers intestinaux. Paris, 1858. 4to, with 



12 pi. 

 KUCHENMEISTER, F. Die in urid an dem Korper des lebenden Menschen vorkommenden 



Parasiten. Leipzig, 1855. 8vo, with 14 plates. 

 LEUCKART, R. Die menschlichen Parasiten und die von ihnen herruhrenden Krank- 



heiten. I., Leipzig, 1863 ; II., Leipzig, 1876. 8vo. 

 COBBOLD, T. Sp. Entozoa ; an Introduction to the Study of Helminthology. London, 



1864. 8vo. Supplement, London, 1869. 

 DAVAINE, C. Traite des entozoaires et des maladies vermineuses de l'homme et des 



animaux domestiques. 2nd edit. Paris, 1877. 8vo. 



