1908-9. ] MICROCHEMISTRY OF STRIATED MUSCLE. 405 
Sudan III at ordinary temperatures, but when either of these fats 
is heated to the melting point in contact with the fat stain the whole 
becomes a deep red. However on recrystallization on cooling the 
majority of the crystals fail to retain their coloration. Mann® does not 
accept the physical explanation for the staining of the fatty materials, 
and suggests that the process is rather one of oxidation. 
The solution used was one prepared by dissolving the Scarlet Red 
powder in 70 per cent. alcohol and allowing it to stand several days. 
Fischer’ claims that a solution made with 70 per cent. alcohol at the 
boiling point or leaving the solution in a parrafin oven for 24 hours, 
produced better results in a much shorter period of time. However, in 
my experiments the additional heating apparently had little effect in 
accelerating the staining and both solutions required, comparatively 
speaking, the same time to give like results. 
Before using the solution all sediment should be removed by 
filtration. Any excess of the stain may be washed off with distilled 
water, as washing in alcohol, even if of a weak dilution, dissolves 
out more or less of the fat, and it is, therefore, not to be recommended. 
The muscle tissue which was found most advantageous for these 
microchemical investigations was that of insects, owing to the size 
of the fibrils and their greater development. In many cases fresh 
tissue was used while in other experiments the muscle was previously 
fixed in 4 per cent. formaline ora 5 per cent. solution of chloral hydrate. 
Previously to being placed in the Scarlet Red, the fibres must be 
thoroughly separated so as to facilitate the penetration of the reagent 
to every part. While a reaction obtains in ten to fifteen minutes it 
appears only in the larger fat droplets or those most readily accessible 
to the staining fluid and the best results, both in detail and distinctness, 
were obtained by leaving the tissue in the solution for five days. When 
allowed to remain longer than this in the staining fluid no further 
trace of fat was revealed, and apparently the reaction was not in any 
way increased. 
When muscle fibres treated according to the methods outlined 
above are examined microscopically the fibrils are seen to be trans- 
versely marked by bright red bands, occurring at regular intervals 
throughout the entire length of the fibre, and under a high magnifi- 
cation these striations are found to be beaded or made up of fine 
granules, which here and there have coalesced to form small globules. 
These striz lie in the dim band, one being along Hensen’s line, across 
