ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
687 
a faint yellow reaction wliere ammonium molybdate alone is present ; 
the great advantage of this reducing agent being that it is not necessary, 
as in the case of pyrogallol, to remove uncombined ammonium molyb- 
date before subjecting the tissues to the reducing process. The method 
is as follows : — The tissues, either fresh or hardened in alcohol, are sub- 
jected, for periods varying from 10 minutes to 48 hours, to the action 
of a nitric-molybdate solution made by dissolving one part by weight 
of pure molybdic acid in four parts by weight of strong ammonia, and 
adding thereto slowly fifteen parts by weight of nitric acid sp. gr. 1 • 2. 
The reagent acts best at a temperature of 35° C., and the action is pro- 
gressive ; the inorganic phosphates are first affected, then the lecithin, 
and finally the organic phosphorus. When the reaction is completed, 
the tissues are exposed to the phenylhydrazin hydrochloride solution 
for a minute or two, washed in distilled water, dehydrated, cleared in oil 
of cedar, and mounted in balsam. The lecithin may be removed from 
the tissues before the phosphorus test is applied by extracting with 
ether and then subjecting to prolonged (five hours) treatment with 
boiling ethyl -alcohol in a Soxhlet apparatus. The inorganic phosphorus 
may be partially removed by treating the tissues with 20 per cent, acetic 
acid ; but it is possible, by examining the preparations after the molyb- 
date solution has acted for about 10 minutes, to determine the relative 
amount of inorganic phosphorus present ; an increase of the reaction 
after the first 10 minutes demonstrates the presence of inorganic phos- 
phorus. 
Microchemical Demonstration of Alkaloids.* — Herr H. Barth, in 
an exhaustive article on the microchemical demonstration of alkaloids, 
states that alkaloids are present in some part of the fruit or seed, from 
the husk to the endosperm and embryo. 
The reagents employed for determining the presence of the alkaloids 
were those ordinarily used in pharmaceutical and toxicological chemistry. 
These reagents were chiefly precipitants, and those which gave some 
characteristic colour. In a few instances the reagents gave better results 
when used as vapour than in solution. 
The results of the author’s observations appear to show that the 
functions of alkaloids are various, some being essentially excretory and 
protective, others, especially such as exist in the endosperm and embryo, 
are reserve substances and nutritive. 
New Method for making Casts.f — Dr. G. A. Peters has invented a 
method for making casts by which the minutest details of the object are 
rendered visible. The process consists in spraying melted paraffin over 
the whole surface, at the same time cooling it by spraying ice-cold water, 
strengthening the mould with plaster of Paris, and removing it in as 
many sections as may be required. The mould is made of hard paraffin. 
The surface of an object requires no preparation unless covered with 
hair. It is in this case oiled, and covered by means of a spray with a 
cream composed of cornflour, glycerin, and alcohol. The paraffin is 
sprayed on through a special ejecting apparatus, which is practically 
nothing more than a spray surrounded by a hot-water jacket. The 
* Bot. Centralbl., lxxv. (1898) pp. 225-31, 261-7,292-300, 326-44, 369-78, 401-9, 
pi.)* t Brit. Med. Journ., 1898, ii. pp. 621-1 (5 kgs). 
