1887.] MICROSCOPICAL JOURNAL. LLG 
\ 
It was stated by Prof. Hanks that while visiting Verdi, Nev., recently, he had come 
across a fossil diatomaceous earth of a peculiar bright salmon color, and there was 
every reason to believe that this deposit was the source of a sample of such earth 
which had been sent to the Society anonymously more than twelve years ago, and 
which had attracted considerable attention at the time by reason of its richness. 
Among the objects exhibited were slides of diatoms and of quartz from Alameda 
beach, mounted by Dr. Riehl, and nine well-stained slides mounted by Dr. Stallard in 
further illustration of the subject of tuberculosis in fowls. 
O 
SAN FRANCISCO, CAL. 
By invitation of Dr. S. M. Mouser, the regular fortnightly meeting of the San Fran- 
cisco Microscopical Society was held in his extensive laboratory last evening, April 
26th., President Wickson occupying the chair. 
It was decided to hold the Society’s annual reception on the evening of May 28th 
next, and the President was authorized to appoint a committee to make the necessary 
arrangements. 
The death of Dr. Allen Y. Moore, a corresponding member of the Society, was 
announced, and remarks eulogistic of the deceased were made by various members. 
Dr. Henry L. Wagner, who has recently completed an extensive course of study in 
the leading biological laboratories of Europe, drew attention to a new organism lately 
found by him, closely allied to the AMcrococcus tetragonus which Koch has observed 
in connection with his investigations on the tubercle bacillus. The cells of the new 
organism occur in characteristic groups of four, and its growth in gelatin is very 
destructive in the appearance of the colonies formed. Dr. Wagner also described and 
gave the formula for a new culture medium devised by him, more particularly for use 
in the study of such organisms as found their natural pabulum upon mucous surfaces. 
Its principal characteristic was the substitution of an alkaline solution of mucin, for 
the peptone usually employed. Dr. Wagner received the thanks of the meeting for 
his interesting address. 
The members then proceeded to inspect the methods adopted by Dr. Mouser in the 
study of bacteria and allied organisms. The various steam-filters, sterilizers (both hot- 
air and steam), incubators, etc., ranged along the sides of the laboratory, were duly 
shown and their operation described. The method of procedure is briefly as follows:— 
Small portions of the material infected by the organism to be studied are placed with 
a needle-point, previously sterilized by heating, either upon the freshly cut surface of 
a boiled potato, which is then covered by a bell-glass, or into a test tube partly filled 
with fluid gelatin which is first shaken thoroughly so as to distribute the introduced 
germs as much as possible, and is then poured upon a glass plate where it hardens, 
and is also covered by a bell-glass. In either case the introduced organisms, rapidly 
multiplying by self division, form small colonies, each original germ being the start- 
ing point of one. Up to this point, the admixture of foreign and undesired germs 
floating in the atmosphere, is unavoidable. It, is, however, an interesting and very 
valuable fact that the colonies respectively formed by different genera, and even spe- 
cies of bacteria and their allies, present marked differences of appearance even to the 
naked eye, so that there is little liability to error from this source. After the colonies 
have grown sufficiently to enable them to be identified, a test tube partially filled with 
a solidified preparation of sterilized gelatin, agar-agar, or similar substance, is quickly 
inoculated by introducing with a needle-point a minute quantity of material from 
what has been ascertained to be the desired colony on the potato or glass plate. The 
test tube is then closed by a wad of sterilized cotton or glass wool and is placed in the 
incubator at the temperature best suited to the contained organisms. The growth of 
the latter is rapid and also distinctly peculiar in the different species, so that an expe- 
rienced investigator, by holding to the light a tube containing a pure culture of such 
organisms, can determine the species merely by the appearance of the colony, which 
sometimes spreads over the top of the gelatin in the tube, sometimes grows only in the 
path made by the needle, and in other cases takes the form of a spiral, a nail, a bunch 
of grapes, etc. Throughout the entire process the very utmost care is taken to prevent 
the introduction of germs other than the one to be studied. Every portion of the appa- 
ratus and the culture-media used are sterilized with the greatest precaution, and even 
the hands of the investigator are bathed in germicide solutions at all the important 
steps of the procedure. When a perfectly pure culture of some germ has been thus 
obtained, the further study of its characteristics, both in the colony and under the 
