264 Canadian Record of Science. 



umes, spoke of the so-called molecular weight as an unknown 

 quantity, although, in accordance with that principle, this 

 molecular weight, or, properly speaking, this equivalent 

 weight, is simply deduced for any body the specific gravity 

 of which is unknown. 



Miscellaneous. 



Solution of Starch in Leaves. — A diastatic ferment can be ex- 

 tracted from green leaves in the following way : — The leaves are 

 bruised in a mortar, and covered with cold water ; after 24 hours 

 they are pressed, and 1J volumes of 90° alcohol added to the juice, 

 which is then filtered. The same quantity of alcohol is again added 

 to the filtrate, and after a few minutes, the clear liquid is filtered off 

 and the precipitate washed once or twice with alcohol of 65°. The 

 diastase is obtained in solution by dissolving the washed precipitate 

 in water and filtering. 10 c.c. of such a solution is added to 0.5 

 gram, of starch into a paste and kept at 63°, and the formation of 

 sugar is shown by comparison with a similar flask to which a few 

 drops of chloroform have been added. The leaves of the potato, 

 dahlia, artichoke, maize, beet, castor oil plant, and the unripe seeds 

 of the opium poppy, sunflower, and castor oil plant, have all yielded 

 positive results. Microbes have not been found in the solution, and 

 the starch was in all cases transformed into a mixture of reducing 

 sugar and dextrine. To connect this with the formation of sugar 

 in growing plants, the author shows, by a series of experiments 

 that, although diastase will only act on starch paste and not 

 on crude starch at 60°, 57°, and 50°, yet at 42° and 34° it always 

 transforms a little crude starch into sugar. The quantity of sugar 

 produced reaches a limit in twenty-four or thirty-six hours ; but if it 

 be dialyzed out of the solution as fast as it is formed, the formation 

 is rendered continuous. The same result is produced by diluting the 

 solution, so that it seems to be the accumulation of sugar which puts 

 an end to the diastatic action. 



Cuboni's experiment, therefore, in which the disappearance of 

 starch from a vine leaf, placed in the dark, was prevented by an 

 annular incision in the stem above and below the leaf, does not 

 negative the idea that starch is transformed into sugar by a diastatic 

 ferment in the leaf : arrest of sugar formation would, under these 

 circumstances, be brought about by accumulation of sugar in the 

 isolated leaf. When only one incision is made, either above or 

 below the leaf, the starch disappears as usual ; and when a grape 

 cluster, either in flower or fruit, is opposite the leaf, the starch dis- 

 appears, even when the stem is cut through above and below. It 

 appears from this that the demand for fresh supplies of carbo- 

 hydrates in some centre of growth will drain off the accumulated 

 organ with sufficient rapidity to render its formation continuous. — 

 Ann. Agronom., 12, 200-203. 



