116 PRACTICAL HISTOLOGY. 



example. With this end a piece of the muscle is 

 teased in a drop of salt solution. This fluid has the 

 effect of gradually disintegrating the proper sub- 

 stance of the muscle, so that the latter tends to 

 break down into a clear fluid with numerous fine 

 granules suspended in it, and exhibiting an active 

 Brownian movement. This process of disintegration 

 generally begins at places where the fibres have been 

 touched by the needles in the process of separation, 

 and if the muscle be fresh, the contractile substance 

 breaks and shrinks away at these places, leaving the 

 clear sarcolemma bridging across the interval. 



Preparations 7 and 8. Disks and Fibrils. In 

 order to exhibit the manner in which muscular tissue 

 tends to break up into either disks or fibrils accord- 

 ing to the nature of the reagent to the action of 

 which it is submitted, two pieces of muscle are taken 

 for an animal that has been dead some hours, and 

 are placed for a week, the one in a solution of hydro- 

 chloric acid (1 in 50), the other in a solution of 

 chromic acid (1 in 200). Small portions are then 

 broken up as finely as possible with needles upon 

 separate glass slides. The fibres from the hydro- 

 chloric acid are, many of them, found to cleave into 

 transverse clear disks, some of which will be noticed 

 lying flat, others seen edgeways ; whereas in those 

 from the chromic acid there is no tendency what- 

 ever to form such disks, but on the contrary, the 

 muscular fibres tend to break up into smaller and 

 smaller longitudinal fibrils. 



Preparation 9. In order the better to compare 

 the fibres either of the same or of different muscles 

 as regards length and diameter, and to see their 

 general shape, it is necessary to isolate a number of 

 them in their whole length. For this purpose the 

 process of separation by the aid of needles is some- 

 what tedious, and we must turn to reagents which 

 will dissolve the intermediate connective tissue 

 which binds the fibres together, whilst maintaining 

 them intact. Such a reagent is to be found in a 



