SPONTANEOUS GENERATION. 23 



proved by experiment to resist the prolonged action of boiling 

 water. As regards Vibrios, Bacteriums, Spirillums, etc., it has 

 not yet been shown that they have spores ; the existence of them 

 is simply inferred from analogy. It is certain that Vibrios are 

 killed by being immersed in water, the temperature of which 

 does not exceed 200 F. We have found all motion, except the 

 Brownian, to cease even at 180 F. We have also proved by 

 several experiments that the spores of common mould are killed, 

 both by being exposed to steam and by passing through the 

 heated tube used in the experiments described in this article. 

 If, on the one hand, it is urged that all organisms, in so far as 

 the early history of them is known, are derived from ova, and 

 therefore from analogy we must ascribe a similar origin to 

 these minute beings whose early history we do not know, it 

 may be urged with equal force, on the other hand, thai all ova 

 and spores, in so far as we know anything about them, are de- 

 stroyed by prolonged boiling : therefore from analogy we are 

 equally bound to infer that Vibrios, Bacteriums, &c., could not 

 have been derived from ova, since these would all have been 

 destroyed by the conditions to which they have been subjected. 

 The argument from analogy is as strong in the one case as in 

 the other." 



On the 4th of August, 1863, Prof. Wyman put into my hands, 

 for examination, the contents of a sealed flask which he had just 

 opened, and which was prepared according to the method (B) 

 on the 22d of July previous, i. e. thirteen days before. I directed 

 my attention particularly to the structure 

 of the Bacteriums, (fig. 8, a, b,) which floated 



in immense numbers throughout the fluid. 



Ordinarily, the central part of the guitar- 6 Fig 



shaped body is occupied by a dark oval mass, as I have described 



it in fig. 6, but in this examination, by the help of an immensely 



Fig. 8. a, 6, Bacterium (Zooglcea) termo. Duj. 3500 diameters. Two of the 

 most diverse forms, with a granulated centre and transparent ends. Original. 

 c, d, Spirillum. Spiral thread-like bodies oftentimes seen among decaying sub- 

 stances in fluids. They whirl with great velocity. Original. 



