74 Muscular Tissue. 



in one of the large water beetles, Hydrophylus 

 piceus. There is another water beetle often sold 

 for this purpose which does not answer so well, the 

 Dytiscus marginalis, it may be distinguished by being 

 smaller and having a yellow line round the margin of 

 the upper surface. 



Fresh Preparation of Muscle to show the Sarcolemm,a. 

 Kill the beetle and remove one of the legs, open the 

 chitinous covering and snip off a bit of the muscle, 

 place it on a slide in a drop of distilled water, tease it 

 out, cover and examine. The sarcolemma will be seen 

 in places raised from the muscle substance. 



Irrigate the same preparation with dilute acetic acid 

 and the nuclei of the muscle corpuscles will soon come 

 into view. 



To make a permanent preparation stain a small por- 

 tion of the leg muscle with logwood, tease it out care- 

 fully into as fine fibrils as possible in a drop of glycerine 

 on a slide, cover and seal up with Hollis' glue. Dissect 

 out some of the muscles of the thorax and mount in the 

 same way. Examine the muscles in a transverse sec- 

 tion of the tongue of any animal prepared in chromic 

 acid mixture and double stained with picro- carmine 

 and logwood. 



3. Heart Muscle. Sections made from the heart of 

 any small mammal will show the peculiarities of this 

 variety of muscle fibre. Make transverse and longi- 

 tudinal sections, and stain them with logwood. Note 

 the position of the muscle corpuscles in the transverse 

 sections, and the anastomosing of the fibres in those 

 cut longitudinally. 



