691 
ZOOLOGY ANS) BOTANY, MICROSCOPY, ETC, 
bacteria throve best on those which contained 15-20 ccm normal alkali 
per litre. 
Influence of Glycerin in Culture Media on Diphtheria Bacillus.*— 
Dr. A. M. Gossage finds that the addition of 9 per cent, glycerin to the 
culture medium gives very favourable results for the cultivation and 
staining of the diphtheria bacillus. Glycerin-serum is preferable to 
glycerin-agar, as the growth is usually greater, and the appearance of 
the bacilli more characteristic. Cultivated on glycerinised media diph- 
theria bacilli exhibit an increased affinity for alkaline methylen-blue, 
and also a specific metachromatism. On these media each bacillus shows 
a deep violet dot at each pole, with frequently one or more dots between 
them, whilst the remainder of the bacillus is colourless or deep blue. 
Other bacteria in the same culture stain blue. 
Dr. A. A. Kanthackj’ states that metachromatism with alkaline 
methylen-blue is not dependent on the presence of glycerin in the 
cultivation medium, and that as a staining phenomenon it is not only 
well known, but common to numerous bacilli. 
(2) Preparing- Objects. 
Preparation of Embryos of Limulus Polyphemus.]: — Prof. W. Patten 
found that surface views of opaque embryos were useful for some pur- 
poses. In order to make out many important details it was, however, 
absolutely essential to stain the egg, and clear in clove-oil, balsam, or oil 
of cedar. The last often gave the best pictures, and the eggs could be 
kept longer in this fluid without discolouring the yolk. To obtain the 
best surface view the embryos should be stained and mounted as soon as 
possible after hardening, or preserved in perfectly clean alcohol in 
glass-stoppered bottles. The use of glass stoppers is necessary as the 
tannin or other substances in cork stoppers are dissolved out by alcohol 
and discolour the yolk. Either picronitric or undiluted picrosulphurio 
acid, or Perenyi’s fluid may be used for hardening. The eggs should be 
immersed in the cold solution from 10-21 hours. After the eggs are 
shelled they are rinsed in the hardening fluids, and transferred to a 
large quantity of alcohol of about 94 per cent., which is changed fre- 
quently the first few days. The most beautiful surface views are 
obtained by staining the whole egg in borax-carmine or almost any 
haematoxylin for a very short time, and then wash in acid alcohol. This 
method gives very sharp and luminous contours. If the eggs are to be 
mounted after clearing in oil of cloves they should be split in halves 
with a sharp knife, made by grinding the end of a needle down to a 
very thin blade. 
Examination of the Sense-Organs of Lumbricus.§ — As Miss F. E. 
Langdon has discovered sense-organs in the epidermis of the earthworm, 
which have been so often overlooked by competent observers, she thinks 
it well to give an account of the methods employed by herself, although 
the account contains little that is new. To ensure successful cutting of 
sections, it was found best to feed the worm on wood-pulp, in the pre- 
paration of which no chemicals had been used. In killing, great care 
* Lancet, 1896, ii. pp. 458-9. f Tom. cit., pp. 531-2. 
% Jouru. Morphol., xii. (1896) pp. 23-7. § Op. cit. xi. (1896) pp. 194-6. 
