ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
357 
bodies (spores) were predominating, and by the dilution method pure 
cultures of a Mycetozoon were obtained. Great difficulty was experi- 
enced in getting rid of bacteria, but this was finally overcome by frequent 
transference to fresh solid and occasionally fluid media. The me lium is 
easily prepared ; 30 to 40 grm. of hay or straw were boiled with 1 litre 
of water, and to the filtrate 1— 1^ per cent, of agar added. The mixture 
is then boiled until the agar is dissolved, and then Na 2 C0 3 added until 
the reaction is alkaline. Wo filtration is needed, for when sterilised, pre- 
cipitates are deposited and in no way hinder observations on the cultures. 
Of course the medium can be prepared in the usual way, if so desired. 
Though the author claims to have obtained bacteria-free cultures by his 
method, in another place it is admitted that this result is scarcely 
possible. 
Diagnostic Medium for Coli and Typhoid Bacteria.* — Herr Eisner 
has found in potassium iodide a substance which imparts to nutrient 
media a capacity to diagnose between typhoid and coli bacteria. Gelatin 
is boiled with potato extract (1/2 kg. to 1 litre of water), and to 10 ccm. of 
the gelatin 2*5-3 ccm. of 1/10 normal soda solution are added. The 
liquid is then filtered and sterilised. When necessary, only 1 per cent, 
of potassium iodide is added. In 24 hours colonies of B. coli are easily 
distinguished from those of B. typhosus , in that the former are quite 
large and the latter tiny. The latter are further described as small, 
bright, watery-like, finely granular colonies, which contrast strongly 
with the coarsely granular brownish coli colonies. 
Diagnosis of Cholera by Means of Cholera Anti-Bodies.j — Prof. R. 
Pfeiffer and Dr. Vagedes have devised a method for diagnosing cholera 
vibrios by the aid of the serum of cholera-immune animals. The serum 
used was of such power that 1/15 mg. sufficed to destroy 2 mg. of a 
living virulent cholera culture. A 1 : 50 bouillon dilution of this serum 
was made, and then hanging drops, inoculated with a trace of cholera- 
culture, examined under the Microscope. The inhibitory effect was very 
marked, the vibrios losing their mobility and aggregating into little heaps. 
Only rarely slightly mobile vibrios were observed, and after 20 minutes 
in an incubator the last traces of mobility were lost. Microscopical 
examination showed that the vibrios were morphologically unaltered. 
After an incubation of 24 hours, the vibrios in the hanging drops were 
found to have multiplied, were in lively motion, and the little clumps 
were barely observable, showing that the inhibitory effect of the serum 
had passed off. Other vibrios were not affected by cholera serum, and 
the authors claim that the specific inhibitory property of cholera serum 
is a valuable aid for diagnostic purposes. Seventy cholera cultures and 
twenty species of vibrios were examined by this method, which is merely 
an application of Pfeiffer’s specific immunity reaction. 
Demonstrating Capsules of Micro-Organisms. + — Herr W. Noetzel 
* Zeitschr. f. Hvg. u. Infektions., S.A. xxi. (1895). See Centralbl. f. Bakteriol. 
u. Parasitenk., l te Abt., xviii. (1895) pp. 590-1. 
t Centralbl. f. Bakteriol. u. Parasitenk., l te Abt., xix. (1896) pp. 385-7. 
X Fortschr. d. Med., xiv. No. 2. See Centralbl. f. Bakteriol. u. Parasitenk., 
P* Abt., xix. (1896) p. 498. 
