~~ 
TRANSACTIONS OF SECTION TI. Boe 
6. Chlorides are absent from chlorophyll corpuscles (Twdipa and Iris), and from 
the chromatophore of Spirogyra and Zygnema. 
7. In Spirogyra and Zygnema the chlorides are confined almost wholly to the 
peripheral protoplasmic membrane, or layer, lining the cell-wall. Very frequently 
a like distribution is found in the chlorophyll-holding cells of the higher forms 
(iris, Tulipa). 
5. Some Points in the Micro-chemistry of the Nerve Fibre. 
By Professor A. B. Macatuuw, J?h.D., and Miss M. L. Menten, B.A. 
The silver reaction of tissues in the presence of free nitric acid having been 
shown by the senior author to be due_to the formation of chloride of silver and 
the reduction of this in sunlight to the dark subchloride, it was used to determine 
the occurrence and mode of distribution of chlorides in the nerve fibres. The use 
of nitrate of silver, as is well known, serves to show the occurrence of the nodes 
on the fibre, and the reaction obtained extends some distance on either side of the 
node, usually in the shape of rings, known as those of Frommann. This reaction 
the authors now find is dus to chlorides, which seem to diffuse towards the nodes 
to meet the reagent diffusing into the fibre. The result is a series of deposits in 
the shape of bands or zones; but this disposition of the precipitate is wholly due 
to physical causes, as it may be obtained also in capillary tubes filled with egg 
albumin or gelatin and placed in a solution of nitrate of silver. In other words, 
the deposits of the subchloride of silver are in bands or zones, while in the intact 
fibre the chlorides are uniformly distributed throughout the length of the 
axon. Where the reagent gets a free entrance to the axon, as may obtain in 
specially made preparations of the spinal cord, the reaction may be quite uniform 
along the axon and without an interruption, That the reaction is due to chloride 
may also be shown by using mercurous nitrate, which gives a precipitate of 
mercurous chloride, and this, after removal of the precipitant, may be revealed by 
the addition of ammonium sulphide. The result of the employment of this re- 
agent is to show exactly the same distribution as revealed with nitrate of silver. 
The conductivity of the axon for nerve impulses is undoubtedly dependent on 
the presence of chloride of sodium, not free between the molecular aggregates of 
the colloid, but enclosed in them, the superficial layer of each of which, acting as 
a semi-permeable membrane, diminishes the velocity of the charge-bearing ions. 
WEDNESDAY, AUGUST 30. 
The following Papers were read :-— 
1. The Life-history of the Coloured Labourer in the Transvaal. By Lovis 
G. Irvine, M.A., M_D., B.Sc., and Donatp Macautay, M.A., M.B., 
C.M. 
This paper dealt with only one aspect of the larger native-labour question, 
namely, the description of the conditions under which the native labourer lives and 
works, and was meant to form an introduction to the actual inspection of these 
eosons by the members of the Association at their visit to a ‘compound’ hos- 
pital. 
The author therefore described where the native labourer comes from, how he 
gets to the Rand, what his work consists in, how he is treated, and how he fares, 
The following were the main points discussed :— 
1. Sources of the native-labour supply. Contributions of the various territorial 
areas, 
2, Methods of recruiting by the Native Labour Association. Regulation of 
recruiting. 
