286 GENERAL ANATOMY OR HISTOLOGY OF BLOW-FLY. 



smaller elements united together. The anisotropous substance 

 is readily stained, the isotropous remains unstained, by carmine 

 and aniline stains. 



I shall use the nomenclature adopted by Schafer [136], and 

 term the primitive fibrillas sarcostyles. Each sarcostyle 

 (PI. XVII., Fig. i) consists of a series of sarcomeres, anisotro- 

 pous substance, cemented together by a cement material, 

 isotropous substance. A fibre consists of a number of sarco- 

 styles, imbedded in a more or less abundant intermediate 

 substance, in which the muscle nuclei lie. This I regard as 

 the undifferentiated reticular protoplasm of the muscle. 



With regard to the alleged structure of the sarcomeres, I 

 have made many preparations from the wing muscles, in 

 which they are most easily isolated, and it appears to me 

 that each consists of a highly refractive flat or prismatic 

 rod, in which I have sought in vain for evidence of more 

 minute structure. It may be, however, that the means at my 

 disposal are inadequate for any further resolution of structure, 

 and as in every other point my observations entirely agree 

 with those of Biitschli and Schewiakoff, I only wish to record 

 the fact that I have been unable to resolve the sarcomeres, as 

 they have done, into more minute constituent rods. My rod- 

 like elements, sarcomeres, measure 'ooi mm. in diameter, and 

 from '002 to 4 oo6 mm. (2" to 6") in length, whilst the ulti- 

 mate elements described by the authors named are only '0006 

 to '0008 mm. in length. 



By teasing the wing muscles in Flemming's mixture, it is 

 quite easy to isolate the sarcostyles, and it is only a little more 

 difficult to attain the same results from the muscles of the 

 larva. The ordinary muscles of the imago cannot be so 

 separated, but the thinnest sections indicate that they only 

 differ from the other forms of muscle in the small quantity of 

 interstitial substance, and the greater density of the reticulum, 

 which plays the part of a sarcolemma. 



When the muscle fibrillae are stretched, the sarcomeres 

 become narrow in their equator, and they then appear strap- 

 shaped (PL XVII., Fig i, b). 



