INVERTEBKATA, CRYPTOGAMIA, MICROSCOPY, ETC. 297 



about 45°. ChloropLyll, therefore, which has been compared to a 

 wax, a resin, and a fat, is really analogous to bilirubine in properties, 

 reactions, and elementary composition. 



Like bilirubine, it is soluble in ether, chloroform, petroleum, carbon 

 bisulphide, and benzine, and is precipitated from its solution some- 

 times in a crystalline, sometimes in an amorphous state. It presents 

 another resemblance to that substance in playing the part of a weak 

 acid, yielding soluble instable salts with the alkalies, insoluble salts 

 with all other bases. The alkaline solutions of both substances are 

 very readily altered and oxidized under the influence of incident 

 light. Both substances yield a number of coloured derivatives — 

 yellow, green, red, and brown. Finally, both substances possess the 

 projjerty of uniting directly with nascent hydrogen. When chloro- 

 phyll is digested with hot concentrated hydrochloric acid, it separates 

 into two substances, one with a beautiful blue-green solution, the 

 phyllocyauic acid of Fremy, the other phylloxanthin, insoluble in 

 hydrochloric acid, but forming a brown solution in ether or hot 

 alcohol, from which it readily crystallizes out. Gautier suggests 

 for pliyllocyanic acid the comj)osition CiyH^.^N^jOs, that of bilirubine 



being C,,H,sNA. 



The author believes that Hoppe-Seyler's chlorophyllan is nothing 

 but his own pure crystallized chlorophyll. The former gives the 

 percentage composition of chlorophyllan as C 73*4, H 9*7, N 5*62, 

 O 9-57, P 1-37, Mg 0-34 per cent.; while Gautier makes that of 

 chlorophyll C 73 • 97, H 9 • 8U, N 4 • 15, 10 • 33, phosphates 1 • 75 per 

 cent. 



In commenting upon this article, M. Trccul points out * that as 

 long ago as 1865 he sejiarated green crystals, soluble in alcohol 

 and ether, which gave birth directly to grains of chlorophyll. 



In response to a question of M. Chevreul,t Does chlorophyll form 

 a constituent jiart of the organ or is its occurrence merely accessory 

 and without organic activity ? M. Trecul replies + that it is important 

 to distinguish between the globular tufts of green crystals and the 

 grains of chlorophyll from which they are produced. The former 

 are not, while tlie latter certainly are, living organs. The principlo 

 known as chloro2)hyll never exists by itself in the vegetable tissue, 

 but always associated with protoplasm, usually in the form of chloro- 

 phyll-grains. 



M. Gauticr's reply to this question § is that the only function of 

 chlorophyll is the decomposition of carbonic acid imder the influence 

 of light. The chlorophyll pigment appears to be only a secondary 

 agent, destined to absorb chiefly tlie red and orange rays of light. 

 Tlius luminous force, transformed in the leaf into heat and chemical 

 action, is utilized by the i)rotoplasm of the chlorophyll corpuscles, to 

 bring about the ueccssary reductions in tlie green parts of plants. 



Finally, M. Priugshcim || calls attention to his microphotochemical 

 experiments, with which physiologists are already acquainted. 1| 



* 'Coniptes IlonduH,' l.xxxix. (1S71>) p. 883. t il>i<i., p. !H7. 



X Il-id., p. 'JT2. § Il>i<l.. p. 'MK II IMil., xc. (1880) p. IGl. 



^ See tliia Juuruul, tintc, p. 117. 



