No. 5.] MISCELLANEOUS. 319 



The next point determined by Dr. Pringsheim, is that the 

 effects are not produced in an atmosphere devoid of oxygen. This 

 was the case whether the oxygen was replaced by pin e hydrogen 

 or by a mixture of hydrogen and carbon dioxide; while the re. 

 moval of the carbon dioxide from atmospheric air was altogether 

 without effect on the phenomena. The conclusion drawn is that 

 the decomposition of chlorophyll in the living plants is a process 

 of combustion which is influenced and promoted by the action of 

 light, and which is not related to the decomposition of carbon 

 dioxide by the plant. When the green color of the chlorophyll- 

 grains has been partially destroyed, it cannot be restored, even 

 though the cell continues to live ; from which it is inferred that 

 the result is not a normal physiological, but a pathological effect. 

 No substance was found in the cells which might be regarded as 

 the product of the decomposition of the chlorophyll, nor was any 

 oil or starch detected in the etiolated cell, nor any formation 

 of grape-sugar or dextrine. The assumption is therefore that 

 the products of decomposition are given off in the gaseous form. 



The conclusion is drawn that the decomposition produced in the 

 protoplasm, and in the other colorless cell contents, is the direct 

 effect of the photochemical action of light. That it is not due to 

 the injurious influence of the products of decomposition of the 

 coloring matter of the chlorophyll, is shown by the fact that it 

 takes place equally in cells destitute of chlorophyll, such as the 

 hairs on the filaments of Tradescantia, the stinging hairs of the 

 nettle, &c. It is, on the other hand, dependent on the presence of 

 oxygen, or is a phenomenon of combustion. 



The results of a variety of experiments leads Dr Pringsheim 

 to the important and interesting conclusion that the chlorophyll 

 acts as a protective substance to the protoplasm against the inju- 

 rious influence of light, diminishing the amount of combustion 

 or in other words, acting as a regulator of respiration. 



He than proceeds to investigate what are the substances which 

 become oxidized in the process of respiration. In every cell, 

 without exception, that contains chlorophyll, Pringsheim finds a 

 substance that can be extracted by immersion in dilute hydro- 

 chloric acid for from twelve to twenty- four hours, to which he 

 gives the name hypoclilorin or hypochromi/l, and which he believes 

 to be the primary product of the assimilation of the chlorophyll. 

 It occurs in the form of minute viscid drops or masses of a semi, 

 fluid consistency, which gradually change into long red-brown 



