194 PROCEEDINGS OF THE CALIFORNIA 



were examined without any previous treatment. It is possible that when freed 

 from tlie earthy and organic matters, one or two other species may be found. 

 There can, however, be no doubt that the waters of the Geysers do not afford a 

 congenial medium for the production of diatoms. In the heated waters of Ne- 

 vada Springs, and in those of Calistoga, they flourish in the greatest abundance, 

 as many as thirty or forty different species being found in one spring ; whilst 

 here, in springs the temperature of which ranges from 195 degrees to 112 de" 

 grees, not more than two or three species have been met with, and but very 

 few individuals of each species. Undoubtedly the cause of this absence of dia- 

 toms is to be found in the character of the waters, which appear to be all acidu- 

 lated by the presence of free sulphuric acid, so that no alkaline silicates can 

 exist ; and as the diatoms are undoubtedly dependent for the silica that forms 

 their skeletons on the soluble alkaline silicate, it is evident that these waters 

 cannot afibrd a congenial place for their development. Other forms of algae 

 seem to flourish in the greatest luxuriance in these mineralized waters. The 

 Doctor had never before seen such masses of oscillaria as are found in the bed 

 of the creek of Geyser Cunon, and their presence in the highly-mineralized 

 waters of a spring, the temperature of which was 174, would show how great 

 is the range of the conditions in which these forms of plant-life can be de- 

 veloped. 



Dr. Cooper alluded to the formation of microscopic plants in 

 M'hite globular masses in dilute sulphuric acid. 



Dr. Kellogg said such formations were common in electric bat- 

 teries, even forming on the surface of copper plates so as to interfere 

 with their efficiency. He also mentioned a cryptogam which was 

 not destroyed in an oven, and did not see why it would not live in 

 water at 212 degrees. 



Dr. Blake said that these facts had some bearing on the ques- 

 tion of spontaneous generation. 



Mr. Durand referred to a late examination made by him of the 

 salts precipitated from the vaporous exhalations at the Geysers. 

 He found large quantities of sulphate of ammonia, which is very 

 scarce in the natural state. 



Dr. Cooper announced the discovery by himself of a fossil tooth 

 like a saurian's, but considered by Professor Agassiz as possibly 

 related to Ai-chegosaurus, before known only in the carboniferous. 

 Having been found in the alluvial drift of Mare Island, its exact 

 position is uncertain ; but if carboniferous, it must have been trans- 

 ported from the northern Sierra Nevada, at least. 



