Appendix. 



the strongylus gigas that makes its abode only in the hilum of 

 the kidney; then there are others peculiar to the brain, the liver, 

 cellular tissue, etc. These creatures long puzzled and completely 

 defied the naturalists in their efforts to explain the mode of their 

 origin, and it is a curious study now to look at the shifting opin- 

 ions which from time to time have been entertained regarding 

 them. To illustrate : Linnaeus, the celebrated naturalist, thought 

 that the internal parasites were terrestrial or aquatic animals that 

 had been swallowed with the food or drink. Bremser and Rudolphi, 

 after twelve years of research, disproved this by showing that there 

 was nothing in common in organization between such parasites 

 and any known species. Boerhaave suggested that there was 

 some metamorphosis or monstrous growth that occurred in them 

 in their new and unaccustomed habitats. This was a leaning 

 toward the truth, for we do find remarkable changes in successive 

 stages of development, but the error was in the starting point. 



Without dwelling further upon their opinions or without an 

 attempt to detail the progress of the study, it is sufficient for my 

 purpose to say that at last all these parasites were found to come 

 from eggs, and in turn to produce young by sexual generation.* 

 Years upon years of the closest investigation were necessary to 

 complete this study, and the nature of the difficulties to be con- 

 tended with were such that it seemed almost impossible to over* 

 come them. This is well illustrated by the cysticerci, the inter- 

 mediate stage or larval forms in the development of the tape- 

 worms. They live in a closed cyst in the solid tissues, and they 

 are absolutely sexless and unprovided with generative apparatus. 

 To connect them, then, with the mature parasite, which lives in 

 the alimentary canal alone, was a difficult task. The painstaking 



* As late as 1858, Pouchet, the uncompromising advocate of the theory 

 of spontaneous generation, questioned the truth of these discoveries in the 

 generation of parasites. Says the writer in the Edinburgh Review (loc. dt.\ 

 " like a true Frenchman of the feebler sort he says, " tant pis pour les faits /" 

 and rejects the facts which reject his hypothesis. He doubts the truth of 

 these discoveries, " the monopoly of which." he naively says, " has by a sing- 

 ular anomaly belonged to foreigners." This reminds one of the pious patri- 

 otism of Lamartine, who said that when God has a noble idea to vouchsafe 

 to mankind He always puts it first into the brain of a Frenchman. 



