1894.] MICROSCOPICAL JOURNAL. 243 



arates it in places. An aqueous solution of iodine will 

 make the membrane more apparent by coloring it yel- 

 low. Tear it off. We thus obtain fibres in which the 

 striated substance is broken within the membrane and 

 leaves, between the ends, a space where the sarcolemma 

 is very apparent. (Formula for the solution of iodine : 

 Water, 100 ; potassium iodide, 6; iodine, 4. Dilute with 

 water if the stain is too intense.) 



Muscular Fibres ; Nuclei.^. . . .If a bit of muscle is 

 put on a slide with a drop of the 40 per cent potash so- 

 lution, a slight teasing with needles will give admirably 

 isolated fibres. Examine in the same liquid as they can- 

 not be preserved. Permanent preparations are made 

 after maceration in the J alcohol. Skin a frog and put 

 a hind leg in the I alcohol. In 24 hours remove a bit 

 of the sartorius, and dissociate on a slide by partial dry- 

 ing. Stain with picro-carmine for ten minutes ; apply 

 the thin cover, and wash gently by running a drop or 

 two of water under the cover, replacing it by acetic or 

 formic acid glycerine. 



Muscular Fibrils. — The fibrils of insects show, in an 

 exceedingly elegant way, the transverse striation of the 

 contractile substance. Select a beetle and remove the 

 elytra and the wings. Cut open the thorax so as to ex- 

 pose the wing muscles which will appear as a whitish 

 mass. Place in the 1-3 alcohol for 24 hours. With 

 curved scissors cut off a bit and dissociate it on a slide by 

 partial drying. Stain deeply by an old preparation of 

 hsematoxylin. Mount in balsam. 



/Sections. — . . . .Put a frog's hind leg in a 2 per cent 

 bichromate solution. After 10 days remove the sartori- 

 us muscle, wash, hardened in alcohol, embed in gum. 

 Transverse sections are the most instructive. Stain by 

 haematoxylin and eosine ; mount in balsam. .. .It is 

 necessary to section also the muscle of a mammal as the 

 arrangement of the nuclei is different. 



