28U Prof. E. A. Schafer. On the Minnie Structure of the 



The effect of the faint fog in increasing the value of [V] = \V 

 is plainly seen in the morning observations. The effect also of 

 very few faint fleecy clouds is seen in the increase of [V] and 

 [U] for the observations at l h and l h 30, before which no cloi 

 had been visible. The air was saturated the whole day. 



The candles which I used in all these observations, were thi 

 " Belmont Sperm," supplied to me so as to burn 100 grs. iu 

 minutes. 



" On the Minute Structure of the Muscle-Columns or Sarc 

 styles which form the Wing-Muscles of Insects, 

 liminary Note." By E. A. SCHAFER, F.R.S. Receiv 

 December 15, 1890, Read January 8, 1891. 



[PLATBS 4 & 5.] 



The fibres of the wing-muscles of most insects are made np 

 readily separable longitudinal elements, which are often called t! 

 " wing-fibrils," although several observers have remarked the exi 

 ence of an apparently fine fibrillation in them. To avoid ambigui 

 I shall employ the term " muscle-columns " (Muskel-tdulchen, K 

 liker), or its equivalent " sarcostyles,"* to designate these elemen 

 They are united together to form the fibres by a not inconsiderab 

 amount of granular interstitial substance (sarcoplasm, Rollett 

 This substance has been regarded (Ram<5n y Cajal) as the true 

 tractile material of the muscles, but it is easy, nevertheless, 

 observe the contraction of the sarcostyles, isolated in white of e, 

 a fact which has been pointed out by more than one writer on 

 subject (Merkel, Kolliker). 



If an insect of which the wing-muscles are of the cha 

 above described is cut open and placed in alcohol of about 90 p 

 for twenty-four hours or more, and is afterwards transferred 

 glycerine, the sarcostyles of the wing-muscles can be isolated 

 examined without difficulty; they exhibit almost every phase 

 extension and retraction (or contraction), and the usual appearani 

 of alternate dark and light transverse bands, with a fine li 

 traversing each light band. When stained with dyes, such 

 haematoxylin, the dark bands are found to take the staining m 

 intensely ; the fine transverse lines are much less stained, and 

 clear bands hardly at all. The various parts of the sarcoflM 

 evidently differ from one another in their behaviour to staining 

 reagents, and the transverse striation is not to be explained by thi 

 effect of the varicosities of the sarcostyle upon the light transmittet 



* ap(, flesh, ari>\o(, a column. 





