ON THE MOLECTJLAH ORIGIN OF INFUSORIA. 
57 
ones, which can only take place where that mass is considerable 
and floating on the surface of deep fluids, directly confirms the 
molecular theory of growth, and offers an illustration of how 
successive disintegrations give origin to different formations.* 
I That the infusoria originate and are developed in the mole- 
cular pellicle which floats on the surface of putrefying or fer- 
i menting liquids, has been admitted by all who have carefully 
I watched that pellicle with the microscope, more especially by 
1 Kutzing,f Pineau, J Nicolet,§ Pouchet,|| Jolly and Musset,^ 
; Schaaffhausen,^* * § and Mantegazza.ff The question therefore is, 
I are the molecules that constitute that pellicle derived from the 
air or the fluid — are they precipitated from above, or do they 
float to the surface from below, like the globules of the milk 
: which produce cream ? 
Now, it was in consequence of having professed to demonstrate 
what had escaped all previous observers — viz. the germs in the 
air — that M. Pasteur has made his name so famous. He tells 
usj{ that he did so by causing a current of air to pass through 
a glass tube in which a pledget of gun-cotton had been placed. 
This was then dissolved in ether, and the sediment allowed to 
i collect in a watch-glass. This sediment, after being repeatedly 
I washed, and allowed to remain in distilled water for twenty-four 
, hours at a time, is allowed to dry. A portion of the dried 
matter is then put upon a slide moistened with a weak solution 
! of potash, and, being covered with another glass, is examined 
with the microscope. The results he has figured ; and, very 
. properly, he has given the scale of magnifying power under 
which they were drawn (fig. 10), and which, by careful measure- 
ment, I have ascertained to be 180 times linear. These are his 
drawings, carefully copied. 
He says figs. 6 and 7 represent organised corpuscles from 
dust collected in twenty-four houis, from November 16 to 17, 
1859. The manner in which the.e drawings, giving tLe volume 
and outline of the bodies, were made, is as follows : “ After the 
dust has been prepared in the manner described, 1 took a por- 
* See On the Molecular Theory of Organisation/’ hy the Author. 
“Proceedings of Koyal Society of Edinburgh/’ 1861. 
t See Schaaff hausen, “ Comptes-Rendus/’ tome liv. p. 1046. 
t “Annales des Sciences Naturelles,” 3me serie, tome hi. p. 182. This 
observer thinks he saw disintegrated fibres of meat and of other substances 
formed directly into vibriones ; in this he was incorrect. 
§ “ Arcana Naturae/’ tome i. p. 2. 
II “ Heterogenie/’ p. 353. “ Nouvelles Experiences,” p. 111. 
^ “ Comptes-Rendus,” tome 1. p. 934. ** Ibid, tome liv. p. 1046. 
tt “ Institut Lombard,” 1852, tome iii. 
Jt “ Annales des Sciences Naturelles,” 4me sdrie, tome xvi. p. 25. 
