1864. | Samuzison on the Source of Living Organisms. 611 
I have also seen plant-cells in great number and variety, and on 
one occasion the contents of my vessel were, after a few days, tinged 
green with Protococcus pluvialis, as much as if they had been taken 
from a rain-water cistern. 
“‘ Vibrio,’ “ Monas,” and the other types of the partisans of 
heterogenesis, were of daily occurrence. 
In all these cases, I have not the slightest doubt that the atmo- 
sphere was the medium through which the germs or spores were 
conveyed into the distilled water, and it was often a matter of surprise 
to me that such a number and variety of forms should have become 
even partially developed, where so little nourishment was afforded 
for their increase. Let me also add that, contrary to what has been 
stated by the advocates of heterogenesis, I have always found that 
the more freely the water was exposed to the air, and the warmer 
the temperature, the more abundant and diversified were the living 
types, and the more rapid was their development.* 
2nd. I have examined dust shaken from samples of various kinds 
of cotton rags which had been imported from the following localities :} 
Egypt, Japan, Tunis, Trieste, Melbourne, and Peru, and in all these 
different kinds I have found well-marked types of protozoa.t To a 
great degree these types differed from those which I had observed in 
dust at home, being more active, and highly organized. 
In one case I succeeded to some extent 
in tracing the growth of several of those 
obscure little forms known as “ vibrio” to } 
the annulated, ciliated type here delineated, 
and saw them cast off ring after ring, which 
then assumed an independent existence, 
and commenced to subdivide and extend 
in length. 
Fic. 7.—Various stages of a Vibrion found in the dust from 
blue Egyptian rags. a. An animalcule 1-150th of an inch 
inlength. 6. The animalcule casting off several ciliated 
rings. 
As, however, it may be objected, with some show of reason, that the 
living types from such sources as these afford no direct proof of their 
presence in the atmosphere (although it is well known that the dusty 
rags imported into this country are for the most part picked up in the 
streets abroad), I am content to let this evidence go for what it is 
worth in the eyes of my readers, and mention the matter chiefly as a 
hint to microscopists where to seek new types of protozoa; but if 
there be any who are disposed to doubt the presence in the atmosphere 
of the germs or zoospores of many of those common infusorial types 
which are supposed by the partisans of “spontaneous generation” to be 
abnormally produced from the infusions in which they are often met 
* T have been the most successful with a shallow white saucer. 
+ The dust was in all cases carefully sifted through muslin on to the surface 
of distilled water, and fell to the bottom of the vessel as a fine deposit. 
{ As described in short memoirs read before the Academy of Sciences, Paris, 
1863 ; and Sub-Section D, British Association, 1863. 
