II. INTRODUCTION. 15 



have examined the ah' itself for such bodies, by passing a current through clear 

 water. This was done by means of a bottle, with two tubes passing through a cork 

 stojiper; one tube dipping into the water, the other reaching not quite to its sur- 

 face. By sucking upon the latter tube, a current of air passed through the former, 

 and was deprived in its course of any solid particles. Ordinarily, when the atnro- 

 sphere was still, early in the morning, or in the evening, neither spores nor animal- 

 cules could be detected. When piles of decaying sticks or dry leaves were stirred 

 up, or the dust was blown about by the wind, a host of most incongruous objects 

 could be obtained from the air ; none, however, wliich could be supposed capable 

 of producing disease. 



To assert, under these circumstances, that there are spores and animalcula3 capa- 

 ble of giving rise to epidemics, but not discernible by any means at our command, 

 is absurd, as it is only saying in other words that such spores and animalcnlaj are 

 liquid and dissolved in the air, or in a condition of chemical solution. That the 

 air may be poisoned by matters incapable of detection by the chemist is proved by 

 the emanations from such plants as the Ixhus vernix, Hipxiomane mancinella, etc. 



Parasites of Man. — The list of described species of parasitic animals and plants 

 to which man is liable is already a long one, but nevertheless, in different parts of 

 the world, others will yet be discovered. According to the most authentic sources, 

 the known species are as follow : — 



ENTOZOA IIOMINIS. 



Filaria medinensls, Gmclin. Subcutaneous areolar tissue. 



Filaria hronchialis, Rudolplii. Bronchial glands. 



Filaria vcuK humani, Nordmann. Ey.e. 



Tiicoceplialus disjyar, Riid. Large intestine. 



Sironyybi^ gigas, Rud. Kidncj-s. 



Ascaris lumlricoicks, Lin. Small intestine. 



Ascaris alaia, Bellingliam. Small intestine. (Ireland.) 



Ox)/uris vermiciilaiis, HremscT. Rectum. 



Spiroptera hominis, Rud. Urinary bladder. 



Ancijclostoinnm duodenale, Dulimi. Sm.ill intestine. 



Trichina spiralis, Owen. Muscles. 



PentasiomuiH conslrictum, Siebold. Small intestine and liver. (Egypt.) 



Bothrioccphalus latus, Brcmser. Intestines. 



Tcenia solium, L. Small intestine. 



Tcenia nana, Siebold. Small intestine and liver. (Egypt.) 



Monostomum lentis, Gescheidt. Crystalline lens. 



Bistomum hejiaticum, Abilgaard. Gall-bladder and portal vein. 



Disfomiim lanceolatum, Mehlis. Hepatic duct. 



Distomum oculi humani, Gescheidt. Capsule of crystalline lens. 



Distomum hcematobium, Bilharz. Portal Vein. (Egypt.) 



Distomum heterophyes, Siebold. Small intestine. (Egypt.) 



Tetrastomum renale, Chiaje. Kidney. 



Hexathyridium pinguicola, Treutler. Ovary. 



Hexathyridium venarum, Treut. In the venous blood. 



Cysticercus cellulosce, Rud. Areolar tissue of various organs. 



Echiiwcoccus polymorphus, Diesing. A'arious viscera. 



