1880. ] Botany. 205 
ammoniacal solution of cupric oxide be so concentrated that the 
whole of the rays of a less wave-length than 0.00051 mm. are ab- 
sorbed, a rapid and powerful effect is produced, although the 
amount of heat that passes is very small. It is thus seen that the 
phenomena in question are not the result of heat. 
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 pure 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 decom- 
position 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 assump- 
tion is therefore that the products of decomposition are given o 
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 pres- 
ence 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 then proceeds to investigate what are the substan i s which 2 
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 
Sives the name hypochlorin or hypochromyl, 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 consistenc hi f ge into long red-bro' 
< < Consistency, which gradually change into long red-browi 
imperfectly crystalline ‘iceiles. It is soluble in alcohol, ether, 
