414 TRANSACTIONS OF THE CANADIAN INSTITUTE. [Vou. VIII. 
of the figure the potassium is isolated in the dim band, in the upper 
contracted part it occurs in the vicinity of the light band and between 
the two extremes the intermediate grades are obtained. 
As already mentioned a comparison of the distribution of the 
chlorine of chlorides with that of potassium in muscle reveals a remark- 
able similarity in the disposition of the two, hence the inference that in 
striated muscle they possess an analogous distribution. j 
Also to be noted is the ease with which the fibril may be broken 
across at the light band, when it is free from any reaction. This 
structure may become so reduced in size as to be scarcely discernible 
except where the fibrils have become divided transversely (Fig. 25) 
through pressure on the cover glass. 
V—THE DISTRIBUTION OF THE PHOSPHATES. 
If fresh tissue, after having been thoroughly teased, be left in a 
decinormal solution of silver nitrate, the phosphates, chlorides and some 
other constituents of muscle which unite to form insoluble compounds 
with silver are precipitated, and in the sunlight these compounds are 
reduced, and assume a deep brown colour. The reagent should be 
prepared from distilled water free from any chemical impurity and 
every precaution should be observed to prevent the tissue becoming 
chemically contaminated. In these experiments as in those demon- 
strating the chlorides and potassium only glass or quill points should be 
used for teasing purposes. A characteristic reaction is obtained when 
the fibres have been in the reagent about three days, after which the 
tissue is then mounted in 50 per cent. glycerine and exposed to the 
action of direct sunlight. 
The compounds in muscle fibre other than the chlorides and 
phosphates which unite with silver to give “ reduced” silver products in 
sunlight, are probably present only in infinitesimal quantities and thus 
when the reagent is allowed to act on muscle fibre in the manner 
described the result is due to “ reduced” silver phosphate and chloride. 
If the preparations before exposure to sunlight are treated with dilute 
nitric acid the “reduced” phosphate does not appear subsequently. 
Consequently, by comparing préparations made to show the chlorides 
alone with those treated with nitrate of silver but not with dilute nitric 
acid, one is enabled to determine, not strictly and definitely, but on the 
whole approximately, the distribution of the phosphates. By compar- 
