232 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. Tlie 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 f to the sun in open, or even in closed 

 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 crust 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 exactlj- 

 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. 



t Similar results are obtained from distilled water, though far more rapidly 

 when mixed with organic substances. 



