VIII.] STRUCTURE OF CONTRACTILE TISSUES. 85 



tinct ; in others the transverse markings will be 

 more or less obscured by an appearance of longi- 

 tudinal fibrillation. Occasionally fibres are met 

 with, having only a confused granular aspect. 

 If the preparation has been successfully made, 

 waves of contraction may, at times, be een to 

 travel along the fibres. 



Observe in the fibres with distinct transverse 

 striation, that, 



a. The dim band has a faint longitudinal stria- 

 tion, as if made up of small rods. 



b. The bright band shews a dotted line running 

 across its centre, thus dividing it into two 

 parts. If the preparation be good, and a 

 high magnifying power be used, this may be 

 seen to consist of two rows of dots. 



c. The usually round nuclei, imbedded in a 

 granular mass of protoplasm; the whole 

 forms a band or rod running a variable 

 distance in the substance of the fibre (cp. 

 5o). 



8. Imbed a small piece of mammalian muscle, 

 hardened in chromic acid *5 p.c., and cut trans- 

 verse sections, stain with hsematoxylin, and mount 

 in glycerine. Observe 



a. The connective tissue (perimysium) around 

 the bundles of fibres and around the whole 

 muscle, from this runs a small amount of 

 connective tissue (endomysium) between the 

 muscle fibres. 



