The Year-Book of Pharmacy

Abstract

THIS volume contains the transactions of the British Pharmaceutical Conference at Hastings in August 1884, in addition to abstracts of papers relating to pharmacy, materia medica, and chemistry, from July I, 1883, to June 30, 1884. The work is of course especially intended for chemists and druggists, but it also contains some information to general readers, and as this might be apt to be overlooked from the special nature of the work, we shall extract from it somewhat more largely than we might otherwise do. Amongst the most striking facts it contains is an observation of Sachs regarding the effect of light on plants, mentioned by Mr. Williams, President of the Conference, in his address. This observation is not only interesting in itself but it appears to give a reason for the rules which the herbalists, centuries ago, laid down for the collection of medicinal plants, and which in modern times have been regarded as simple nonsense, and have consequently been abandoned. The herbalists were particular about collecting their herbs at certain hours of the day or night, and even at special phases of the moon. We have not yet got any exact information regarding the effect of the moon upon the chemical composition of plants, but Sachs's observations show that the amount of starch present in the leaf of any given plant varies considerably under different circumstances. In direct sunshine and under otherwise favourable circumstances, starch is formed very rapidly; but it generally disappears entirely during the night, so that a leaf collected in the evening will prove full of starch, while another leaf of the same plant collected before sunrise will not show a trace. But even in direct sunshine, with all the necessary warmth and moisture, the plant will not form starch if the air in which it is growing be deprived of carbonic acid by means of caustic soda. The method of ascertaining the presence of starch in a leaf is very simple. “The leaf to be examined is first plunged into boiling water for about ten minutes, then taken out and digested in alcohol for about the same time (methylated spirit answers perfectly well). This treatment extracts the whole of the colouring-matter (chlorophyll), and leaves the leaf perfectly white. The leaf is now placed in an alcoholic solution of iodine, and the presence or absence of starch is demonstrated in a few minutes. The absorption of iodine commences at the edges, and soon colours the leaf blue-black if much starch be present, or brown if the quantity of starch be but small. The venation of the leaf appears as a pale network on a dark ground, rendering it a very beautiful object, but all my efforts to preserve a specimen beyond a few hours have hitherto failed.” The variations in the amount of starch in the leaves at different periods of the twenty-four hours are peculiarly interesting as rendering it probable that the amount of alkaloidal or other active principles may also vary in a similar way. Since the publication of this book other researches have been made which render such a variation all the more probable inasmuch as they show that some of the poisonous alkaloids formed by the putrefaction of albuminous substances are identical with those occurring in some plants.

Year-Book of Pharmacy, 1884.

(London: J. and A. Churchill, 1884.)