ON PARASITES. 11 



ity of success is, under the circumstances, sufficiently dubious. 

 Speculations based upon negative evidence, though interesting and 

 supported by numerous analogies, are not reliable, from the impossi- 

 bility of knowing all the circumstances that bear upon the case in 

 point. It seems proved, however, that the germs of future organisms 

 float in myriads through the air and in the water, and that they lie 

 everywhere upon the surface of the earth. 



Man is accustomed to pride himself upon his position at the head 

 of animated nature, yet in the exercise of those powers which are 

 his prerogative he exposes himself to vicissitudes and dangers that 

 he often does not appreciate, and from which the inferior animals are 

 more or less exempt. Accustomed from his birth to one climate he 

 rushes into a very different one, and retaining his original habits 

 under very different circumstances, he pays a double penalty for his 

 rashness : first, of disease ; secondly, of the entozoa to which that 

 disease supplies a suitable nidus for development; In seeking his 

 pleasure wherever and whenever he lists, fortunate indeed is it for him 

 thai; he affords so few conditions as he does for the development of 

 parasites. For does he scent the perfumed gales from the orange 

 groves of the south, or snuff the cold air from off the icebergs at the 

 north, he takes into his aerial passages the invisible germs of future 

 organisms. Does he tickle his palate with the delicious fruits of the 

 tropics, or make a frugal meal like the Esquimaux, of train oil and 

 tallow, on the shores of the Arctic sea, down his throat by thousands 

 go the dormant seeds of future evil. Insinuated into his lungs, nose, 

 mouth, and cutaneous follicles, and scattered over his whole body, 

 the microscopic germs await their destiny. 



This much, the microscopic and other observations absolutely 

 demonstrate. That single experiment of Schultz of Berlin, is con- 

 clusive upon this point, and at the same time confutes most of the 

 arguments in favour of the generatio equlvoca. He took a flask and 

 placed in it a vegetable infusion. A cork with an apparatus of two 

 tubes bent to a suitable form and with bulbs blown upon them, was 

 carefully inserted into the flask, sulphuric acid was placed in the one 

 tube, and in the other caustic potash. Air from time to time was 

 sucked through the tubes and consequently through the flask also. 

 After a couple of months the infusion remained free from cryptogams 

 and infusoria. The cork was then removed and the infusion exposed 

 to the air, in a few days the infusion swarmed with life. During the 



