BY PROF. WM. H. BREWER, OF THE STATE GEOLOGICAL SURVEY.
More than two years ago I laid before this Society some facts in regard to the growth of plants in the thermal waters of this State. Since that time we have more observations, and some of the facts are worthy of record, although the fact is not new that plants will grow in hot water.
At the Geysers in Lake County, there are numerous hot springs and steam jets, in and around which there is an abundant growth of a low form of vegetation (Nostoc?) growing on the soil and covering it with a bright green coating. In some of the warm springs and streams it accumulates in considerable quantities in the water. The highest temperature of water observed at the time of our visit, in 1861, was 207° F.; the water of many of the springs boiling violently at temperatures ranging from 196° to that stated. This vegetable flourished in waters of the temperature of 200° F., but was most abundant where the temperature ranged from 125° to 140° F. It coated the soil around the steam jets, where it would be alternately exposed to the jets of steam issuing at a higher temperature than that of boiling water, and of the cooler air.
In water of the temperatures of 100° to 125° there are filamentons algæ.
At the Little Geysers similar facts were observed.
In Plumas County, near Lassens Peak, there are three groups of hot springs, at all of which the same form of vegetation is abundant under similar conditions, especially around steam jets. Various gases, especially sulphohydric and sulphurous acids, accompanying the steam in all of these localities, and the soil is generally impregnated with various saline substances. All the specimens of the plants were unfortunately lost, so that no microscopic examination has been made, further than could be done on the spot with a pocket lens.
Near all of these springs, the Panicum thermale Bolander, grows on the saline soils, sometimes where the soil is warm and the grass is subjected to steam; but its station appears to depend more upon the saline character of the soil than upon its temperature. It was frequently found on soil saturated with sulphates of soda, lime, etc., and having a strongly acid reaction.
None of these forms are universally found about all the hot springs of the State; many springs have been visited where neither of them occur, but where one is found the other is generally found also.
Dr. Cooper presented the following paper for Dr. Newcomb, corresponding member: