II. INTKODUCTION. 15 



have examined the air itself for such bodies, bypassing a current through clear 

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

 stopper ; 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 atmo- 

 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, which could be supposed capable 

 of producing disease. 



To assert, under these circumstances, that there are spores and animalcule 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 animalculse 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 Blius vernix, Hippomane 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 HOMINIS. 



Filaria medinensis, Gmelin. Subcutaneous areolar tissue. 



Filaria bronchialis, Rudolphi. Bronchial glands. 



Filaria oculi liumani, Nordmanu. Eye. 



Tricocephalus dispar, Rud. Large intestine. 



Strongylus gigas, Rud. Kidneys. 



Ascaris lurnhricoides, Lin. Small intestine. 



Ascaris alata, Bellingham. Small intestine. (Ireland.) 



Oxyuris vermicularis, Bremser. Rectum. 



Spiroptera Jiominis, Rud. Urinary bladder. 



Ancyclostomum duodenale, Dulimi. Small intestine. 



Trichina spiralis, Owen. Muscles. 



Pentastomum constrictum, Siebold. Small intestine and liver. (Egypt.) 



Boihriocephalus latus, Bremser. Intestines. 



Tcenia solium, L. Small intestine. 



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



Monostomum lentis, Gescheidt. Crystalline lens. 



Distomum hepaticum, Abilgaard. Gall-bladder and portal vein. 



Distomum lanceolatum, Mehlis. Hepatic duct. 



Distomum oculi humani, Gescheidt. Capsule of crystalline lens. 



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



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



Tetrastomum renale, Chiaje. Kidney. 



Hexathyridium pinguicola, Treutler. Ovary. 



HexatJiyridium venarum, Treut. In the venous blood. 



Cysticereus cellulosce, Rud. Areolar tissue of various organs. 



Echinococcus polymorphus, Diesing. Various viscera. 



