PROCEEDINGS OF SOCIETIES. 
329 
Mr. Chantrell, Honorary Secretary, drew attention to an elaborate 
paper, well illustrated by Professor Taylor, " On Fungoid Diseases of 
Plants," which appeared in the Annual Eeport of the Commissioner 
of Agriculture for the year 1871. 
The President exhibited and described a number of lichens and 
mosses which he had collected during his recent scientific expedition 
in the ' Argo,' many of which were extremely rare, and several new to 
science. 
The meeting concluded with the usual conversazione. The exhi- 
bition of microscopes being unusually large, there was a good attend- 
ance of members and visitors. 
San Francisco Microscopical Society.* 
A regular meeting of this Society was held at its rooms in Cali- 
fornia Street last Thursday evening, Vice-President H. 0. Hyde in 
the chair. 
Mr. Moore exhibited a section of the trunk of a pine of a very 
peculiar variety, whose history he will fully elucidate at the next 
meeting. Dr. Wythe exhibited a sertularian polyp from Monterey Bay, 
covered with diatoms of various sorts, navicular and sertularite, &c. 
The specimen was interesting from its novelty, and the question 
arises as to whether the polyp was the habitat of the diatoms or the 
latter an accidental accretion. 
Fourteen Mock Sections from the Comstock Mines, hy Melville 
Atwood. — The slides marked Nos. 1, 2, and 3, are sections of rocks 
from what, at the Gold Hill portion of the Comstock, is known as the 
Black Dyke. The specimens from which they are cut were taken 
from the Dyke at different depths below the surface, at 1100, 1400, 
and 1740 feet. I have made a careful examination of them, and think 
they are from a basaltic rock belonging to the class called Dolerites, 
in confirmation of which, these sections will be seen to consist of 
crystals of Labradorite and Augite, imbedded in a greyish paste or 
matrix, in which are also numerous minute particles of magnetic 
iron — presenting that mottled appearance so characteristic of that 
class of volcanic rocks. 
Slide No. 4 is a section of Dolerite and Anamesite, from Bol- 
vershahn, in Siebengebirge. It resembles the Black Dyke so much 
that I can hardly distinguish any difference between them. 
Slides No. 5 and 6 are sections from the unaltered trachytic 
greenstone. Specific gravity 2 * 7. Contains silica 52 p. c. 
Slides No. 7 and 8 are sections of the altered trachytic greenstone. 
The green mineral so conspicuous in these altered rocks is smarag- 
dite. Slides Nos. 9 and 10 are sections from what may be called 
" True Horse," found in the ore bodies. 
Slides Nos. 11 and 12 are sections from the Comstock ore, 
showing how the argentiferous gold is mechanically mixed with 
the silver ore. 
* [Unfortunately the Secretary sends us these Keports without any date 
whatever.— Ed. ' M. M. J.'] 
