SPONTANEOUS-GENERATION CONTROVERSY. 451 



and recent instance will suffice. After a remarkable series of experi- 

 ments detailed before the Royal Society, Dr. W. Roberts says : "The 

 issue of the foregoing inquiry has been to confirm in the fullest man- 

 ner the main propositions of the panspermic theory, and to establish 

 the conclusion that bacteria and torulce, when they do not proceed 

 from visible parents like themselves, originate from invisible germs 

 floating in the surrounding aerial and aqueous media." ' 



But, farther, this has been remarkably sustained by analogical evi- 

 dence. There are putrefactive organisms that closely approximate 

 to the bacteria in form, structure, and size. These are the " monads" 

 or, as Prof. Huxley doubtless more fitly names them, the heteromati? 

 They live side by side with the bacteria in the same putrescent mass, 

 and certainly in the later stages of the disintegration of dead organic 

 matter are the most active and powerful agents. From their greater 

 size they present a more promising field for microscopical research 

 than the bacteria themselves; and the life-history of some of there 

 could be fully mastered. I long since felt that valuable aid might 

 thus be rendered to the discovery of the nature of the bacteria. 

 Armed with the best and most powerful appliances which the modern 

 optician could supply, Dr. J. Drysdale and myself ventured on the 

 work. The results are fully detailed elsewhere. 3 It need only be re- 



)\ 





iSw 4JN? 



. > " , - ** 



' . . '. :. 



Fig. 1. 



marked here that the only hope of success was in continuous observa- 

 tion of the same form, in the same drop of fluid, under the highest 

 powers. The secret, therefore, was to find a means of keeping the 

 same drop under examination without evaporation. This we did. 4 

 The result was, that patient work enabled us to completely unravel 



1 "Philosophical Transactions," 1874, p. 475. 



2 Macmillan's Magazine, February, 1876, p. 379. 



3 Monthly Microscopic Journal, vols, x.-xiii . 



4 Ibid., vol. xi., pp. 67-69. 



