1076 REPORT—1885. 
undoubtedly full of a wonderful chemical energy, and the most complicated syn- 
theses are performed with ease. Think of a bacterium, that lives and multi- 
plies in acetate of ammonia solution, and forms its albumen, fat, and cellulose 
from this compound of so simple a composition! Think of the continued produc- 
tion of protoplasm that goes hand in hand with the perpetual destruction by 
respiration, and certainly a most energetic chemical activity becomes evident. 
In 1875 the first attempt was made to trace this energy back to a peculiar 
chemical constitution of the albumen that composes the protoplasm. The physio- 
logist E, Pfliiger, in Bonn, was the author of this hypothesis. He believed the 
albumen to contain cyanogen groups, which take up the elements of water, and 
thus the albumen would lose the agility of the atoms and change into another 
substance of less chemical energy—the dead albumen. 
This hypothesis hardly found the recognition it deserved. It was only Detmer,. 
Professor of Botany in Jena, who in 1880 accepted and defended similar views. 
In his opinion the chemical change of the albumen takes place by atomic displace- 
ment, and while in the living albumen a most energetic motion of the atoms leads 
to a continual dissociation, this ceases entirely in the dead or ordinary albumen.. 
Neither Detmer nor Pfliiger made any experiments whatever. 
Tt was in 1881 when, starting from my own hypothesis of the formation of 
albumen in plants, I was led to the conclusion that the albumen of the living 
protoplasm contains aldehyd groups which are lost in the albumen of the dead 
protoplasm by atomic displacement. I therefore concluded that these easily 
changeable and energetic aldehyd groups could be demonstrated by the action 
upon an alkaline silver solution. Living cells should give a reduction of the 
silver solution, dead cells should not. The first experiment succeeded, It was 
made with an alga named Spirogyra, The slides were exhibited, which under the: 
microscope demonstrate this difference very clearly, the protoplasm is perfectly 
black in one case, and not at all in the other case, where dead cells (Ixilled by a 
temperature of 50°, or by an acid) had been submitted to the silver reagent. This: 
silver reagent shows still action in a dilution of 1 part of silver to 200,000 parts 
of water. Not all objects show this reaction. Objects in which the killing process 
is performed too quickly cannot give the reaction, the silver solution itself being 
poisonous. There can also exist many obstacles that prevent the reaction, as. 
presence of chloride of sodium, existence of an impenetrable membrane, &c, ‘The 
phenomenon known as argyria is probably also founded upon the reaction of the 
active albumen of living protoplasm. In this case the metallic silver is deposited 
in different organs of the human body, when treated internally by nitrate of 
silver. 
The kidneys of frogs and caterpillars show also the reaction, young hairs of 
plants, parts of leaves, roots, and the cells in living wood. Diatoms and in- 
fusoria die altogether too quickly to give the reaction; also some algee of the: 
higher classes behave likewise, and parts of most of the animals. 
Many experiments were made to prove that this reaction is caused solely by 
the character of the albumen of the living protoplasm, It will suffice here to 
mention that I have shown by analysis that the oxygen of the reduced silver 
oxide has really entered into the molecule of the albumen. 
The supposition that the reducing atomic groups in the active albumen are 
nothing but aldehyd groups receives a strong support by the fact that hydroxyla- 
mine proves to be a poison of the most general character. We know that this 
substance acts upon all aldehyds with great readiness, even in a yery diluted and 
perfectly neutral solution. Its poisonous qualities can find no other explanation 
than that it acts upon the aldehyd groups in the living protoplasm, causing” 
disturbances that lead to disorganisation in the cells. 
While these experiments prove that the albumen of the living cell is quite a 
different substance from that of a dead cell, and thus a foundation for an explana- 
tion of the great chemical aetivity of the living cell is furnished, still I am at 
the same time far from believing that hereby all vital action can be explained. 
The cause for the divisions of cells, the nervous activity, the growth after pre- 
scribed rules, the wonderful differentiation of the various functions of a living body, 
