239 DR. CARUS ON THE KINGDOMS OF NATURE, 
characteristics. 2. In the whole calcareous series,—which begins in 
the oldest mountains of our earth, proceeds through all periods, is of 
the greatest magnitude in those of the latest formation, presents in the 
petrifactions the relics of an extinct animalization, and is connected as 
a living member (in the coral-banks), with the existing animal world,— 
nitrogen and hydrogen (the essential elements of the animal world) are 
the principal characteristics. 
The connexion between inorganic and organic life, however, is shown 
more immediately and more clearly in the production of organisms 
from pure water; to which we must refer both the origin of the Infusoria 
obtained by the pouring of water over mineral substances, as observed 
by Gruithuisen, and still more, the origin of the so-called green matter, 
the history of which has been so admirably traced by Priestley and In- 
genhousz. These show more than all other experiments, that in the 
purest water, under the free influence of air, light, and heat, beings are 
formed which, oscillating as it were between the animal and the plant, 
exhibit the primitive germs of both kingdoms. The succession of the 
changes which take place in the formation of the Infusoria is of such 
importance that we cannot avoid considering them more in detail, and 
therefore select from the acute G. R. Treviranus * the following passage 
in reference to those cases. 
“If we expose spring water+ to the sun in open, or even in lesa 
but transparent vessels, after a few days bubbles rise from the bottom, 
or from the sides of the vessel, and a green crust is formed at the same 
time. Upon observing this crust through a microscope, we discover a 
mass of green particles, generally of a round or oval form, very minute, 
and overlaid with a transparent mucous covering, some of them 
moving freely, whilst others perfectly similar to these remain motionless 
and attached to the sides of the vessel. This motion is sometimes 
greater than at others. The animalcules frequently lie as if torpid, but 
‘soon recover their former activity. 
“ As the corpuscles constantly become more numerous, the erust in- 
creases likewise. After a few weeks the latter acquires a certain thick- 
ness and consistency. If we examine it in this state, it appears exactly 
as described by Priestley. It looks in fact like a slimy sediment of the 
water, which has become green under the influence of the sun without 
presenting any trace of organization. The green particles, which were 
visible at the time of their formation, are now so crowded together, and 
perhaps so changed in their organization, that the most attentive ob- 
server, unless he had closely followed their metamorphosis step by step, 
would hardly be able to discover the traces of their primitive form. 
“A few weeks later, when the crust has assumed a still greater con- 
* Biologie, vol. ii. p. 302. 4 
+ Similar results are obtained from distilled vag bgt far more rapidly 
when mixed with organic substances. : 
