PROCEEDINGS OF SOCIETIES. oe 
to investigation, the indirect effect of which had been to 
throw fresh light on the anatomy and life-history of the 
mysterious forms of which the subject treats. It was with 
the latter view, chiefly, that the author laid before the Asso- 
ciation the results of his recent experiments on Atmospheric 
Micrography. 
First, however, he passed briefly in review the leading 
facts connected with the “ Spontaneous Generation” contro- 
versy, referring to the opinions held by the advocates and 
opponents of the doctrine. 
These views have at various times been published in the 
‘ Microscopical Journal,’ and the author quoted the leading 
expressions of Professor Pouchet, of Rouen, Messrs. Jolly 
and Musset, &c., in favour of, and those of Pasteur in oppo- 
sition to, the doctrine, referring his readers to the various 
portions of this Journal in which they appeared for a full ac- 
count of the controversy. He also touched upon the experi- 
ments of Wyman, of Boston, who has recently entered the 
lists as the advocate of heterogenesis, and of his own, which, 
irrespective of those he has published, were rather adverse to 
the doctrine than otherwise. As our readers will think, 
however, Mr. Samuelson’s experiments to be now described 
present features totally opposed to what ought to be expected 
if the doctrine of heterogenesis were true, for he found in 
distilled water, containing the dust of various countries, 
many of the chief infusorial animalcule usually supposed by 
the advocates of ‘“ heterogenesis” to be spontaneously pro- 
duced in infusions of decaying organic matters. 
Let us briefly recapitulate the chief results of these experi- 
ments. In 1862, in conjunction with Dr. Balbiani, of Paris 
(the author of a very accurate and interesting work, recently 
published, ‘On the Reproductive Organs of Infusoria’), he 
exposed certain infusions in Paris and Liverpool, and in both 
places and in all the infusions the same forms were found 
amongst dissimilar ones. Some of these were traced to the 
dust on the windows of the operators, and in one case Mr. 
Samuelson found in pure distilled water, after it had been 
exposed to the atmosphere for a few days, the same form 
(Cercomonas acuminata, Dujardin) as he had found in his in- 
fusions, in dust taken from the high road, and in the cata- 
logue of infusoria forwarded by Dr. Balbiani, as having been 
present in fis infusions. 
Encouraged by these results, the author obtained dust by 
shaking rugs imported from the following countries, namely, 
Melbourne, Japan, Alexandria, Tunis, Trieste, and Peru, and 
these different kinds of dust he kept until June, 18638, and 
