24 SPONTANEOUS GENERATION. 



magnifying lens,* that gave me a power equal to 3500 diameters, 

 I found that this centre was composed of a number of granular 

 bodies, (fig. 8, a, b,) but the ends of the Bacterium were, like 

 those in fig. 6, very transparent ; and, moreover, what gave 

 additional character to these bodies, one end was always much 

 more delicate than the other, at times so excessively faint as to 

 be scarcely discernible. What induced me, among other things, 

 to believe that these bodies were in a peculiar stage of growth, 

 was, as Prof. Wyman had noticed at the same time, that they 

 did not move, as they are ordinarily observed to do. 



From the foregoing observations it is clear that the Bacteriums, 

 found in the sealed flasks, are of a more elevated nature than 

 the simple granules which go by the name of Monads ; in fact, 

 they are even more highly organized than the Vibrio, which is 

 essentially nothing more than a string of Monads moving in 

 concert. Finally, I will add, in confirmation of what I have said 

 in regard to Bacterium, that a German observer, Cohn,f has 

 shown that the Bacterium termo is merely one of the stages of 

 growth of a kind of mould which he has called Zooglcea termo. 



In one of Prof. Wyman's flasks, containing some slivers of 

 beef, sugar, and water, which he had prepared, according to the 

 method marked (B), and boiled 20' on the 2d of Sept., 1864, and 

 which I opened, at his request, on the 25th of Oct., 1864, 1 found 

 large numbers of Bacterium termo oscillating very lively. These 

 I have illustrated and described under fig. 6. The rnoniliform 

 Vibrio (fig. 5, &,) was seen only here and there ; but there 

 abounded another form of Vibrio, which, when seen with a mag- 

 nifying power of only 300 diameters, might be mistaken for the 

 rnoniliform Vibrio ; if, however, they were magnified with a 

 good lens, 500 diameters, their true outlines would become ap- 

 parent. In order to get as clear a conception of their form and 

 nature as possible, I subjected them to the searching scrutiny of 



* One of Tolles's ^ of an inch objectives, made for me with particular refer- 

 ence to the study of the minuter Infusoria and the early stages of cellular de- 

 velopment. 



f See Cohn, Acta Academiae Naturae Curiosorum, 1854; vol. XXIV. pars I. 

 p. 119, and PL xv. fig. 9. 



