150 RECENT RESEARCHES 



densely packed with grafinles, which were just visible when the 

 area was increased six million times ; a group of these granules 

 was watched under the microscope without intermission, and 

 they were gradually seen to develop, until at the end of six 

 hours they had assumed all the characters of adult specimens, 

 and proceeded to complete their Hfe-cycle by reproducing them- 

 selves by the act of self-division. Among the most minute 

 Monads which were observed, a similar act of conjugation 

 was seen to take place, followed by the emission of a similar 

 glairy fluid, but here, at first, no power could detect a single 

 gra7nde,hvii on continuously examining with a lens magnifying 5,000 

 diameters, the spot where the fluid had rolled, within one hundred 

 minutes a number of the minutest conceivable specks came into 

 view (compared by Dallinger to the growth of the stars, in an 

 apparently starless space, upon the eye of an intense watcher in 

 a summer twilight), and these, as in the former case, were carefully 

 watched until they w^ere seen, in the same manner, to develop 

 themselves into the parent condition. Now if the germs of these 

 Monads, the adults of which are three times as large as the 

 Bacterium tci'fuo^ are proved in their earliest stage to be invisible 

 to our highest microscopic powers until they have undergone a 

 certain amount of development, surely it is not incredible that 

 Bacterial germs are for a time equally beyond our powers of 

 vision. 



The balance of evidence certainly appears to me very much 

 in favour of the Atmospheric Germ Theory ; and the conclusion 

 to be drawn is that the Bacteria, in any putrefying infusion, 

 spring, not from any spontaneous combination, but that they are 

 developed from germs which are everywhere floating in the 

 atmosphere, and which have thus obtained admission to the 

 putrescible substance. 



I cannot do better, as a summary of the conclusions arrived 

 at, than give you the words of Tyndall himself: — "From the 

 beginning to the end of the enquiry there is not a shadow of 

 evidence in favour of the theory of Spontaneous Generation. 

 There is, on the contrary, overwhelming evidence against it ; but 

 do not carry away with you the notion, sometimes erroneously 

 ascribed to me, that I deem Spontaneous Generation impossible^ 



