320 THE CANADIAN NATURALIST. [Vol. ix. 



imperfectly crystalline needles. It is soluble in alcohol, ether, 

 turpentine and benzol, but insoluble in water and in a solution of 

 sodium chloride. It becomes gradually oxidized on exposure to 

 an imperfectly crystalline resinous substance. It is probably an 

 ethereal oil, and an invariable accompaniment of the coloring sub- 

 stanc3 of chlorophyll, and even more universally distributed than 

 starch or oil. It has not yet been detected in those plants which 

 do not contain true green chlorophyll, such as the Phycochroma- 

 ceae, Diatomaceae, Fucaceae and Floridese. Starch and oil appear 

 to be reserve substances produced by the oxidation of the hypo- 

 chlorin caused by light, it being the most readily oxidizable con- 

 stituent of the cell, more so even than chlorophyll itself 



That the hypochlorin — present in variable quantity in every 

 chlorophyll grain under normal circumstances — is subject to con- 

 tinual increase and decrease, may be proved without difficulty. 

 All comparative observations on chlorophyll grains in younger 

 and in older conditions, point unmistakably to the conclusion 

 that the collection and increase of the starch enclosed in the 

 ground substance of the chlorophyll, goes on pari passu with a 

 decrease of the hypochlorin. In dark, the hypochlorin, which 

 does not take any direct part in the transport of food materials, 

 is more permanent than starch ; and this fact again is in agree- 

 ment with the conclusion that its transformation in the cell into 

 more highly oxidized bodies is hindered by the increased respira- 

 tion in light. 



In the facts here detailed, and the conclusions derived from 

 them, Dr. Pringsheim believes that an entirely new light is thrown 

 on the cause of the well-known fact that assimilation takes place 

 only in those cells of the plant which contain chlorophyll. This 

 substance acts universally as a moderator of respiration by its 

 absorptive influence on light, and hence allows the opposite phe- 

 nomena of respiration and elimination of carbon dioxide to go 

 on in those cells which contain it. A more detailed account of 

 the experiments and results is promised by the author in a future 

 paper. — American Naturalist. 



Published Mav 7th. 1880. 



