554 REPORT—1905. 
rarely die, The parasite is the largest known. It is carried by Hippobosca 
rufipes. 
(c) Disease caused by a spirillum.—A spirillum causing anemia is found in 
the blood of oxen, especially in poor animals, It is inoculable from the ox to the 
ox and to sheep. The parasite is found in the blood of immune animals; it is 
caused by the blue tick passing through the egg, and is inoculable by the larva. 
3. On the Nature of the Silver Reaction in Animal and Vegetable Tissues. 
by Professor A. B. Macattum, Ph.D. 
When fresh preparations of animal and vegetable tissues are treated with a 
solution of nitrate of silver containing free nitric acid, and then exposed to light, 
they become coloured, the colour varying from reddish to violet. The author 
endeavoured to determine to what the reaction is due. It was found that of 
the organic constituents of tissues the only ones to form compounds of silver 
which reduced under the influence of light were sulphocyanic acid, creatin, and 
taurin. As creatin is present only in vertebrate muscle-fibre, and not at all in the 
tissues of invertebrates, while the other compounds mentioned occur in tissues 
only in infinitesimal, and, therefore, in negligible quantities, the silver reaction 
cannot be attributed to their presence. It was further ascertained that neither 
phosphates, carbonates, nor sulphates give coloured silver compounds in the 
presence of free nitric acid. There remained, among organic compounds in tissues, 
only the proteids, and as these are generally held to form, with silver salts, com- 
pounds ‘reducible’ under the action of light, it was necessary to determine 
whether the coloured compounds so formed are ‘albuminates’ or simply sub- 
choride of silver, For this purpose proteids were freed from chlorides by repeated 
precipitation with pure ammonium sulphate, and it was found that egg and serum, 
albumins and globulins, as well as gelatins, after the eighth precipitation, give no 
reaction whatever with nitrate of silver under the influence of light, and that 
the compounds eliminated by the precipitation, and to which the silver reaction 
is due, are chlorides. Nucleoproteids also were found to be reactionless. In the 
case of vegetable proteids the method employed was different, but the result was 
the same. Silver nitrate in the presence of nitric acid may, consequently, be used 
as a micro-chemical reagent for determining the presence of chlorides in animal 
and vegetable tissues, and its use for this purpose has already given some very 
important results. This reaction, together with that used by the author to 
demonstrate the occurrence of potassium, renders it possible to determine not only 
the presence or absence of haloids, but also, not infrequently, of sodium. 
4, On the Distribution of Chlorides in Animal and Vegetable Cells, 
Ly Professor A. B. Macatium, Ph.D. 
The employment of solutions of nitrate of silver containing free nitric acid on 
fresh tissues, animal or vegetable, followed by exposure of the preparations to 
sunlight, constitutes a valuable method for determining the distribution of 
chlorides in animal and vegetable cells, and it bas been used by the author for this 
purpose. Among the results which have been thus obtained are the following :— 
1. The cell nucleus is, when normal, absolutely free from chlorides. 
2. Chlorides are absent from the head of the spermatozoon (frog, rat, and 
guinea-pig). 
3. The cytoplasm of nerve cells gives an almost uniform reaction for chlorides. 
4, Inert protoplasmic structures, as well as intercellular material, eg., the 
so-called cement substance of Von Recklinghausen, are rich in chlorides. 
5, Chlorides are abundant in the parietal cells of the gastric glands, less abun- 
dant in the chief cells (guinea-pig), and they are more abundant in the granular 
than in the protoplasmic zone of the pancreatic cells (guinea-pig), 
