250 W. M. Baldwin 



and aqueous Solutions of hematoxylin among the latter Schultze's 

 and also Gage's. Several of the more significant of the preparations 

 were stained, decolorized, and then restained by another method 

 in Order not only to serve as controls to the simple stained sections 

 but to demonstrate, in addition, the reactlon of the several struc- 

 tures under consideration to the various methods previously employed. 

 By means of a method of blunt dissection of the fixed and stained 

 preparations upon the slide, several muscle fibres with their tendons 

 were isolated from adjacent struetures, by which was rendered 

 possible a more careful and detailed study of their structural 

 relationship. 



In fig. 1 I have represented such an isolated muscle fibre with 

 its attached tendon of an extrinsic eye muscle of a three-weeks old 

 chicken. The instance is typieal of the usual fibre-termination ob- 

 served in these muscles. It can be seen that the sarcolemma at 

 its extremity is drawn out to three distinct pointed processes which 

 are not in any way continuous either with the sheath of the tendon 

 or with the fibrillar components of the tendon. Furthermore, the 

 pointed extremities of the tendon fibrillae are observed to be inserted 

 into the recesses between the sarcolemma processes. This feature 

 is worthy of special attention because owing to it an appearance is 

 produced, when such au arrangement is rotated and studied in a 

 vertical optical plane, of tendon fibrillae lying inside of the sarco- 

 lemma sheath of the muscle tibre. The individual muscle fibrillae, 

 upon approaching the sarcolemma, lose their several features of 

 cross-striation but can be traced, however, as slender, faintly-stained 

 thread-like struetures up to the internal surface of the sarcolemma 

 upon which they terminate. The sarcolemma is in general much 

 thinner than the cross-diameter of an average muscle fibril. Hence 

 from the morphological arrangement of the parts thus efifected, the 

 muscle tibre appears to be dovetailed into the tendon with this ex- 

 ceedingly thin membrane as the only structure separating the muscle 

 fibrillae from the tendon fibrillae. 



Fig. 2 is another fibre from the same muscle, and demonstrates 

 the same general features. Two muscle nuclei imbedded in granulär 

 protoplasm separate two groups of muscle fibrillae from each other. 

 Each group, however, terminates in several pointed sarcolemma 

 processes which are dovetailed with the fibrils of the corresponding 

 tendon-fibril groups. Here again the muscle fibrillae, losing gradu- 

 ally their features of cross-striation, are, nevertheless, readily trace- 



