196 MR P. BRUCE WHITE ON 



while in fig. 5 the substance of a highly atrophied fibre (A) is contrasted with two 

 normal fibrillse and normal sarcosomes (B). 



The sarcosomes of the atrophied fibre are much denser and more cubical in shape 

 than the normal granules, and may be of relatively enormous size. In highly 

 degenerate fibres they may form conglomerate masses of considerable size. 



When degenerate muscle is treated with dilute acetic acid the fibrillar vestiges 

 swell, forcing the granular columns apart, and a picture closely resembling normal 

 muscle when treated in the same way is achieved. 



When freshly obtained normal and atrophied fibres are placed in a drop of dilute 

 eosin or methylene blue, it is found that while the former are only slowly and 

 superficially stained, the latter become rapidly and deeply stained through their 

 entire substance. This would seem to indicate that the degenerate fibres are dead. 



Though various fixation and staining methods have been employed, they have 

 added little to the facts derived from the study of fresh material. 



These muscle changes may be summarised as — 



A general wastage of the fibrillar substance and loss of sarcous fluid, with the 

 condensation of the frequently enlarged sarcosomes in densely arranged longitu- 

 dinal columns, the process resulting in a shrinkage of the fibre with loss of function. 



All stages in this process are, of course, to be encountered. 



A further feature of some atrophied fibres, and occasionally of those which do not 

 show the typical signs of wastage, is the development of pigmented spots in their 

 substance. Such spots are represented in fig. 5. 



These spots vary in colour from yellow to a deep brown or black, and often 

 appear to bear a definite relationship to the distribution of the tracheoles supplying 

 the muscles. 



Careful scrutiny has not entirely elucidated their origin. It seems possible that 

 they may be caused by staining of the muscle by the faecal dye of the parasite, which 

 has percolated into the final ramifications of the tracheal system. 



Other explanations which have been considered are that the discoloration is due 

 to a degenerative process in the muscle or to an accumulation of waste products. 

 This point may perhaps be cleared up by further work. 



In some diseased stocks these spots are found in almost every crawling bee ; in 

 others, apparently at the same stage of the disease, they are absent. 



The Blood. 



The blood of the crawling bee is often scanty, though when such bees are 

 warmed and fed they recover their normal complement of body fluid. 



No qualitative cytological diff"erence has been noted between the blood of healthy 

 and crawling bees, though the number of cells per unit volume may be increased in 

 the latter. This increase is probably entirely due to loss of plasma and cannot be 

 regarded as a leucocytosis. 



