ZOOLOGY AND BOTANY, MICROSCOPY - , ETC. 
405 
second or two, though I have not found this necessary, as itlie nutrient 
surface does not come in contact with the inside of the cup. The egg 
and shell are, of course, both sterilized by the act of boiling. Five 
minutes’ boiling suffices, and if the operation lias to be done ‘ while you 
wait,’ the egg can be cooled in a still shorter time by placing it in cold 
water. Strict attention to aseptic details is unnecessary as the diphtheria 
bacillus outstrips in its growth the contaminating organisms likely to 
lead to confusion. The appearance of the diphtheria colonies at the 
expiration of twenty-four hours is the same as when they are grown in 
serum, but I have found the growth even more rapid, so that a colony is 
already visible in twelve hours. Confusion with micrococci is, of course, 
to be guarded against. The reliability of this method seems to be the 
same as that of the methods of Haffter and E. Roux. 1 have found one 
bacillus which attains visible dimensions within the same period, but, as 
this also grew on in the manner characteristic of the diphtheria bacillus, 
the great value of the method here described is not invalidated by that 
fact. 
Although this minor modification of a now well-tried procedure 
might enable it to be employed by those destitute of laboratory outfits. I 
do not think it likely that this means of diagnosis will be utilized by 
physicians not habituated to laboratory methods. 
It may be of interest to state here that the constant temperature of 
about 35° C., needful to ensure the rapid and characteristic growths of 
diphtheria bacillus, can readily be obtained by placing in a cupboard oi« 
box with the culture a large jar or pail of warm water, which is renewed 
from time to time, thus making an impromptu thermostat.” 
(2} Preparing 1 Objects. 
New Method of Preparing Spinal Cord.* — Dr. E. Goodall recom- 
mends a new method for preparing the spinal cord for microscopical 
examination, the chief steps in which are : — Place a portion of a cord 
taken from a recently killed animal, and 6 to 8 mm. high, on the ether 
freezing microtome ; free and cut ; float the section, which should be quite 
free from wrinkles, on to water ; take up the section as soon as possible 
with a perforated lifter, drain off excess of water, and float the section on 
pure piridin kept at hand on a watch-glass. One quarter of an hour 
to one hour will probably suffice. Wash well in water ; stain ; de- 
hydrate and clear in piridin ; mount in balsam suitably thinned with 
piridin. Anilin blue-black (1/4 per cent, aqueous solution) followed by 
picrocarmine may be recommended as a staining reagent. 
New Method of Preparing Dentine.f — In this method, suggested 
by Lepkowski, it is stated that sections of bone or dentine may be 
simultaneously softened and stained. The agent used is a modified 
form of Ranvier’s fluid, and is composed of 6 parts of a 1 per cent, 
watery solution of gold chloride to 3 parts of pure formic acid. The 
pieces of teeth, which should be 1/2-3/4 mm. thick, are placed in this 
fluid for 24 hours ; they are then removed, washed with distilled water, 
and placed in a mixture of gum arabic and glycerin for 24 hours. On 
* Brit. Med. Journal, May 1893, pp. 947 and 8. 
f Journ. Brit. Dent. Assoc., xiv. (1893) p. 248. 
