STILL FOUND IN A LIVING STATE. 327 
superior to that of all others, to which indeed I have already 
briefly drawn attention in a remark in my last Memoir on the 
formation of the chalk*, but which I will here treat of somewhat 
more at length. 
In the remarkable mode of reproduction by self-division, and 
in the indifference of these minute independent beings to cli- 
matic variations, there appear to reside characters which suffi- 
ciently distinguish them from larger beings, so as to make them 
pre-eminently adapted to a greater duration and extension 
through entire and successive formation-epochs of the earth. 
a. Climatic relations. 
In the first place, as regards insensibility to climatic varia- 
tions, progressively extended researches have connected the 
most remote districts of the earth by similar living species. 
Europe, Africa, Asia, and America, together with the Islands of 
the Ocean (the Isle of France, the Isle of Bourbon), have abun- 
_ dantly presented perfectly similar minute bodies, partly fossil, 
partly living, in the most varied relations, as has been from time 
to time communicated to the Academy since 1830, and this know- 
ledge has recently received very considerable accessions. More- 
over, an exceedingly extensive diffusion of many similar species 
had manifested itself in fresh water and in the sea; and forms 
had been found on the Siberian Alps of the Altai so coincident 
with those of the Berlin waters, and of the Nile in Dongola, 
that the greater part of those brought with me, when placed 
side by side, and examined together along with the drawings 
sketched after nature, offered to the naturalist no characters by 
which they could be distinguished. 
8. Self-division. 
The other also of the characters above-mentioned, that of self- 
division, had, under continued observation, risen to a most surpri- 
sing power, surpassing all calculation of its possible effect. By this 
mode of production and increase, the Infusoria not only stood 
connected with the other organisms, but they plainly exhibited a 
power of increase and transformation of matter which placed them 
as regards these functions at the head of all other known orga- 
nized beings. The possibility of the multiplying of an individual 
to a million in less than forty-eight hours was exhibited in them 
(without taking into account an abundant development by eggs), 
* Transactions of the Academy of the year 1838, p. 85. 
