1887.] MICROSCOPICAL JOURNAL. 177 
pig. Several of these mounts showed very clearly the tendency of the rods to assume 
the Lepfothrix form, especially in the smaller capillaries. The bacilli were exceed- 
ingly sharp and clear, the staining having been effectively done with gentian viole 
and Bismarck brown. 
Mr. Wickson showed specimens of /cerya purchas? (the cottony cushion scale), and 
dwelt upon the importance of thoroughly studying out the life history of this insect, 
which is inflicting such terrible ravages among our citrus fruit trees. He also showed 
the beautiful eggs of a Penfafoma upon an apricot, while Dr. Bates exhibited the eggs, 
living larva, and perfect insect of a closely allied species of the same genus. 
Another interesting specimen shown by Mr. Wickson consisted of a square block 
cut from the timbers used for bulkheading in the lower levels of the Comstock mines. 
In order to show by contrast the change wrought by the tremendous and long con- 
tinued pressure upon these timbers, specimens of the wood used for them (white pine), 
in a normal state, were also shown. But the effect of the pressure was still more strik- 
ingly apparent in a slide which Mr. Wickson had prepared, showing both transverse 
and longitudinal sections of the compressed and uncompressed woods side by side. 
In the transverse sections the distortion was most apparent, the large, open sells of the 
parenchyma being squeezed out of all resemblance to their former appearance, while 
the effects of the steam and infiltration of hot, ore-bearing waters were seen in a com- 
plete change in the color of the wood. In the longitudinal sections it was an interest- 
ing fact that the glandular dots, characteristic of coniferous wood, which were finely 
shown in the uncompressed section, were completely obliterated in the other. Mr. 
Hanks stated that he had repeatedly made assays of such timbers, and had clearly 
shown the presence of both gold and silver, thus apparently showing that the deposi- 
tion of these metals was a process still going on. . 
Mr. Clark handed in a slide which he had mounted from diatomaceous material 
collected at Tampa Bay, and cleaned by Dr. Taylor, of Mobile, Ala., who is making 
a specialty of working up the blue muds of the Gulf coast. The Tampa Bay gather- 
- ing contains over twenty distinct forms, and is remarkably free from broken frustules. 
In rather striking contrast to the above, a fossil diatomaceous deposit was shown by 
Mr. Hanks, obtained from Hearst’s ranch, San Luis Obispo county, Cal. In this de- 
posit nearly every diatom was broken. This was accounted for by the theory that, 
after the original deposit had been accumulated, it must have been broken up by 
water in a state of violent agitation, and then redeposited. 
A paper on ‘ Errors likely to occur in Microscopical Observations’ was read by Mr. 
Hanks. He dwelt upon the fact that the same object will sometimes make different 
impressions upon the eyes of different observers. For instance, the hemispherical 
‘bosses’ upon certain diatoms are persistently seen by some as cup-shaped depres- 
sions or concavities. As an exemplification of this fact, he had chosen as his exhibit, 
at the late reception of the society, a nickel coin shown under a low amplification. A 
record was kept of a little over two hundred visitors who viewed this coin, and of this 
number some forty saw the elevated portions of the surface as depressions. After 
more prolonged examination, about one-half of these persons was enabled to see the 
coin in its true aspect, still leaving, however, some Io per cent. of the original number 
who were unable to see in any way but as depressions the very evidently raised por- 
tions of the coin. The paper brought out an interesting discussion of the causes pro- 
ducing this peculiarity. 
A. H. BRECKENFELD, 7ec. Secr. 
ie) 
SAN FRANCISCO, CAL. 
The San Francisco Microscopical Society held its regular semi-monthly meeting on 
July 27th, at its rooms, 120 Sutter street, President Wickson in the chair. 
A sample of a newly found deposit of diatomaceous earth was received from R. E. 
Wood, of St. Helena, Cal., and was referred for examination and report. 
Copies of the memorial of William Ashburner, prepared by the Harvard Club of this 
city, were received and placed with the society’s archives. 
Dr. Riehl exhibited a slide under a 1-5-inch dry objective, showing numerous bacilli 
obtained from the sputum of a consumptive patient. In the preparation of the slide, 
the generally approved methods of staining had not been followed, but he claimed this 
had not unfavorably affected the result. In the discussion which followed, and which 
was generally participated in, Dr. Stallard described the staining methods now most 
widely used, and which had been found to yield the safest and most satisfactory results. 
