GROWTH OF FUNGI AND OF INFUSORIA. 333 



extinct species of other animals. The final products are identical 

 in both cases. 



There have been very wonderful and incomprehensible ob- 

 servations mac*e on the behavior and functions of certain mi- 

 croscopic animals. From these observations, there seem to follow 

 conclusions regarding the nutrition and growth of these creatures, 

 quite at variance with all that we know of the process of nutrition 

 of the higher classes of animals. 



In a treatise on the composition of the salt-springs in Hesse- 

 Cassel, Pfannkuch mentions a singular phenomenon, that the 

 slimy mass which deposits in the tub set to receive the brine per- 

 colating through the wells of the graduating-house, contains a gas 

 which is found to be pure oxygen gas. The fresh brine obtained 

 directly from the draw-well is quite clear, and contains 5 per 

 cent, of salt with gypsum and sulphuretted hydrogen in such con- 

 siderable quantity that it might be used as a sulphureous water. 

 During the summer months, a slimy transparent mass forms in 

 this brine, covering the bottom of the vessel containing it to the 

 depth of one to two inches. This matter is everywhere filled 

 with bubbles of gas, of a considerable size, often two or three 

 inches broad ; these rise to the surface, when the membrane in- 

 closing them is torn with a stick. The quantity of these gas- 

 bubbles is so great, that it would be easy to fill hundreds of 

 bottles with them in a short time. They are so rich in oxygen 

 gas, that a glowing match of wood introduced into the collected 

 gas, bursts into flame, and continues to burn with brilliancy. On 

 being analysed, this gas is found to consist of 51 per cent, of 

 oxygen, and 49 per cent, of nitrogen ; but there can be little 

 doubt that the gas originally consisted of pure oxygen, which be- 

 came mixed with the nitrogen of air by virtue of diffusion, just as 

 it does when confined in an animal membrane. In fact, it is 

 found, that when the water in the tubs is very low, the bubbles 

 existing in the deposit appear to be pure air, owing to the celerity 

 with which the diffusion has taken place (Wohler). 



Wohler has subjected to microscopical examination the slimy 

 membranous deposit, and has shown that it consists almost en- 

 tirely of living and moving infusoria, principally species of Na- 

 vicula and Gallionella, such as occur in the paper-like formation! 



