1U0 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
then drying the threads in a sulphuric acid exsiccator. This killed off 
the cholera bacilli, leaving only living amoebae in the cyst form. These 
cysts, when inoculated on gelatin or agar substrata, developed, but did not 
multiply. But by inoculating the cysts on a medium in which bacteria had 
been bred, they grew and multiplied, although they did not, as a rule, 
thrive quite so well as when living bacteria were present. With a 
bacillus isolated from hay, however, the results were practically as good 
as when the cultures contained living bacteria. The medium used was 
composed of 1-1*5 grin, agar, 20 grm. bouillon, and 80 grm. water ; its 
reaction was alkaline. The medium was heated to 60°-70° to kill off 
the bacteria, and then used for the amoeba cultures. 
Cultivating Pleurococcus vulgaris.*— Herr M. W. Beijerinck culti- 
vates Bleurococcus vulgaris in the following medium. Agar is soaked in 
distilled water until all the soluble organic bodies are dissolved out, and 
2 per cent, thereof is added to the following mixture : — distilled water, 
100 parts; ammonium nitrate, 0*05; potassium phosphate, 0*02; mag- 
nesium sulphate, 0*02; calcium chloride, 0*01. Over plates composed of 
the foregoing mixture is poured some of the material rubbed up in water. 
The material is derived from the green deposit on trees, roofs, walls, 
and hedges. The superfluous water having been poured off, the plate, 
carefully protected from dust, is placed in a window with a southern 
aspect. The green colonies show up in about three weeks. The 
author’s first successful cultures were made in the winter of 1890, 
since which he has kept perfectly 7 pure cultures, and these have remained 
constant and monomorphic. 
(2) Preparing- Objects. 
' Application of Engelmann’s Method to the Examination of Animal 
Tissues.^ — As long ago as 1881, Engelmann adopted a method which 
was capable of demonstrating the presence of very small quantities of 
oxygen. The reagents were putrefaction-bacteria, and the material 
green alga cells. A drop of the water was placed on a slide, a few alga 
cells were added, and then a cover-glass was put on. In a short time 
crowds of lively bacteria were found close about the alga cells. The 
addition of blood, muscle, Ac., showed that the liveliness of the move- 
ments and the massing of the bacteria were dependent in the first place 
on the quantity of oxygen disposable for respiration, and in the second 
place, when this is copiously present, on the nature of the added nutrient 
material. Herr A. Exner has applied Engelmann’s method to the exami- 
nation of blood, voluntary muscle, heart muscle, fat, liver, thyroid, frog’s 
ovary, spleen, cartilage, brain and spinal cord, nerve and retina, all of 
which gave a positive reaction ; while bone, lung, skin, gastric mucosa, 
kidney, sub-maxillary gland of cat, pancreas and ovary of rabbit, were 
negative. The bacteria used were Bac. fluorescens liquefaciens and 
B. aquatilis communis. 
Impromptu Method of making a simple Freezing Apparatus.^: — 
Mr. H. E. Durham gives the following prescription for extemporising a 
refrigerator for bacteriological purposes. 
* Centralbl. Bakt. u. Par.. 2 te Abt., iv. (1898) pp. 785-7. 
t Sitzber. k. Akad. Wiss. Wien, cvi. (1897) pp. 58-65. 
t Brit. Med. Jonrn., 1898, ii. p. 1801. 
