On the Winy-Mutclex of Insect*. 



PLATE 4. 



Fig. 1. Part of a sarcostyle which has become fixed in the 

 retracted (? contracted) condition. Fig. la. The same, more 

 magnified. 



Fig. 2. Part of a retracted sarcostyle, showing a slight mechanical 

 dislocation of some of the sarcous elements, which has been 

 produced after hardening. Fig. 2o. The same, more magnified. 



Fig. 3. Part of an extended sarcostyle. Fig. 3a. The same, more 

 magnified. 



Fig. 4. Portion of a sarcostyle, which, at one end, is much 

 extended, at the other moderately extended, these conditio: 

 having probably been present before hardening. The middl 

 part is somewhat dislocated, probably after hardening. Fig. 4a. 

 The same, more magnified. 



PLITB* 5. 



Fig. 5. Parts of three moderately extended sarcostyles, wil 

 granules of the sarcoplasm lying between them. 



Fig. 6. Part of two adjacent sarcostyles, somewhat swollen by tl 

 formic acid. The upper terminal sarcous element of each 

 one is swollen and flattened out, and is lying obliquely, < 

 having been probably touched by the needle in teasing ihc 

 muscle. These show, especially the right-hand one, tht 

 tubular structure of the sarcous elements. 



Fig. 7. Two sarcous elements lying free : one is represented ii 

 profile, the other in optical section. 



Fig. 8. Photograph of part of a microscopic field, containing 

 number of more or less broken-up sarcostyles, and showing 

 several of the sarcous elements lying flat, and others in profile. 

 The tubular or canalised structure is very evident. (Tl 

 globules represented are oil-drops which had accidently 

 into the glycerine in which the specimen was mounted.) 



Fig. 8a. Middle part of the above photograph, enlarged; *, , 

 sarcous elemeuts in profile view. Those to which the lett 

 are adjat.-ent show the line where separation occurs when tl 

 sarcostyle is extended (as in figs. 3 and 3u). Some of the other 

 (bluer) acid-swollen elements, which come out less darkly in 

 the photograph, exhibit the canalisation better. ', ', sarcous 

 elements seen on the flat, i.e., in optical section ; o, o, a i- 

 dental oil-globules. 



Figs. 1 to 8 are photographs taken with Zoiss's 1'30 aperture, 

 2-min. homogeneous achromatic objective, and with projection ocular. 

 They are magnified 870 diameters. Figs, lo, 2a, 3a, &c., are enlarge- 

 ments from the same negatives. They represent the tissue elements 

 'luaguified 2300 diameters. 



