78 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
the diatom Actinocyclus Bnlfsii. Experiments with this diatom are de- 
scribed. 
In illustration of intercostal markings, experiments are described 
with Peristephania Eutyclia. In this connection it is stated that the light 
which does not contribute to delineate anything upon the object is apt 
to intrude in three forms : — either (n) concentrated into patterns which 
are superposed upon the microscopic image ; or (b) scattered in patches 
over part of it ; or (c) spread in the form of a luminous haze over every- 
thing. 
The phenomenon produced by Stokes’s layer (“ Optical Contact ”) is 
then illustrated by experiments with Pleurosigma angnlatum. 
Lastly, the author describes how, by putting a disc with pinholes in 
it over the back of the mounting of the objective, it is possible to actually 
see one of the rulings which go to build up the ordinary microscopic 
image. 
/3. Technique.* 
Cl) Collecting Objects, including Culture Processes. 
Simple Method for Excluding Air from Liquid Media used for 
Anaerobic Cultures.^ — Dr. Th. Kasparek uses a simple contrivance for 
cultivating anaerobes. It consists in having a side-tube (about 1 cm. 
wide) ending in a bulb fixed to the neck of a flask. After the flask has 
been filled up to the neck with bouillon, about 3 ccm. of fluid paraffin are 
poured in. The flask is then placed in a steriliser, when, in consequence 
of the heat, the bouillon rises up the neck and drives most of the 
paraffin into the side-tube. When the flask cools, a thin layer of 
paraffin covers the bouillon. The bouillon is next inoculated and then 
the side bulb heated to remelt the paraffin. By inclining the flask the 
melted paraffin runs out and forms a thick layer over the surface of 
the bouillon. In this way a perfectly air-tight stopper is obtained. 
Of course the paraffin is removed by merely warming the neck of the 
flask and running the paraffin into the side neck. 
Egg-yelk as an Adjunct to Nutritive Media.f — Dr. A. Capaldi 
recommends egg-yelk as an addendum to cultivation media, partly on 
account of its intrinsic chemical proj3erties and partly from the results 
obtained. The yelks of fresh eggs are also said to have the additional 
virtue of being free from germs, for if bacteria be present in the egg 
they reside in the white. The author’s procedure is to crack a fresh 
egg and having removed the white, to place the yelk in a sterilised 
Petri’s capsule. The yelk-sac is then cauterised with a hot glass rod 
at some point. The burnt part having been removed with a platinum 
wire, 3-1 loopfuls of yelk are removed and mixed with the intended 
medium, e.g. agar, which is already prepared. Plates or tubes are then 
made. The medium is yellowdsh and rather cloudy, but the results 
obtained are quite as good as those from blood-serum, while the prepara- 
tion is quicker and more convenient. 
* This subdivision contains (1) Collecting Objects, including Culture Pro- 
cesses; (2) Preparing Objects; (3) Cutting, including Imbedding and Microtomes; 
(4) Staining and Injecting; (5) Mounting, including slides, preservative fluids, &c. ; 
(6) Miscellaneous. 
f Centralbl. f. Bakteriol. u. Parasitenk , l te Abt., xx. (1896) pp. 536-7 (2 figs.). 
X Tom. cit., pp. 800-3. 
