244 



cimens the relation of nerve- fibre, nerve - ending, and sarcolemma are 

 especially well shown 1 ). 



The individual muscle - fibres either run from one tendon to an- 

 other or they may end at one extremity or at both within the muscle- 

 fasciculi which extend from tendon to tendon. We may therefore 

 distinguish two modes of ending of individual muscle-fibres: the "intra- 

 tendinous", where the tip of the fibre terminates within a definite 

 extension of a well marked tendon ; and the "intrafascicular", where 

 the muscle - fibre terminates in the midst of a bundle of other muscle- 

 fibres which have a different region of termination. In the former 

 case the muscle-fibre has a rounded or cone-shaped termination, often 

 swollen in isolated specimens (Fig. 2a). In 

 the intrafascicular mode of ending the muscle- 

 fibre gradually becomes more and more narrow 

 until it finally terminates in a thread-like ex- 

 tremity (Fig. 2b and c). Near the extreme tip 

 of a typical fibre of this kind, isolated from a 



Fig. 2. Tips of muscle-fibres isolated from the ex- 

 ternal oblique muscle of a rabbit, a intratendinous ending; 

 b, c intrafascicular endings. Magnification about 1000 dia- 

 meters. 



rabbit, the fibre was about 4 fi in diameter; 1 mm behind the tip it 

 was 20^ in diameter; 2 mm behind the tip it was 40 (x in diameter; 

 and in the region of greatest thickness, about 2 1 j 2 cm from the tip, 

 100 (.i in diameter. 



After digesting in pancreatin muscle-fibres which have been fixed 

 in osmic acid, the sarcolemma together with a certain amount of the 

 surrounding fibrous tissue, blood vessels, and nerves, may be washed, 

 stained, and mounted in balsam. By staining deeply in Delafield's 

 haematoxylin and counterstaining in Congo red, the fibrous tissue takes 

 a red stain while the sarcolemma retains a bluish tint. This offers a 

 good method of studying the relations of the sarcolemma to the fibrous 

 tissue by which it is attached to the other structures. The sarco- 

 lemma completely incloses the tip of the fibre, both when the ending 

 of the fibre is intrafascicular and when it is intratendinous. In each 

 case small bundles of fibrous tissue are inserted in the sarcolemma at 

 its extremity. What holds them in place it is difficult to determine. 

 When the ending of the fibre is intratendinous these bundles are con- 



1) Bakdeen, Growth and histogenesis of the cerebro-spinal nerves 

 in Mammals. American Journal of Anatomy, Vol. 2, 1903, p. 231. 



