The Kelation of Muscle Fibrillae to Tendon Fibrillae etc. 263 



imperfect fixation or staining we overlook the exceedingly delicate, 

 definitive, cone-shaped, sareolemma processes, the conclusion is natural 

 that the tendon fibrillae and muscle fibrillae are eontinuous because 

 the sareolemma has been perforated. This figure answers the 

 question, as well, as to the relation of the sarcoplasm to the sareo- 

 lemma. Oiir earlier conception of the latter as a closed tube 

 enelosing the sarcoplasm is correct. At no place does the sarco- 

 plasm pass through the sareolemma. At every point this thin enve- 

 lope separates the specialized, semifluid sarcoplasm from the inter- 

 stitial fluids, lymph, etc., of the outlying tissues. 



I have not been able to carry out my studies on either Hippo- 

 campus or Arnphioxus. It would be interesting to explain upon 

 phylogenetic and ontogenetic grounds the differences in the adult 

 morphological condition in these vertebrates from that which I have 

 described above in higher vertebrate muscles. 



As a final word upon the question of the cone-shaped processes 

 of sareolemma 1 desire to repeat with added emphasis, lest some 

 criticisms regarding faulty fixation or shrinkage be made, that as 

 controls to the fixed and stained preparations I studied many prepa- 

 rations of living muscle by vital staining in monochromatic light. 

 Methylene blue aqueous Solutions among others were used and of 

 such a degree of concentration that a control tadpole lived for 

 thirty-six hours in the same fluid which was used to stain the cau- 

 dal muscles. The preparations which I employed were studied ten 

 minutes after the removal of the muscle. No fixatives or dehydra- 

 ting agents whatever were used. In every one of these living 

 specimens the cone-shaped sareolemma processes could be readily 

 found. Therefore, they did not owe their presence to an arte- 

 factitious change in the muscle structure. 



The following general conclusions, theo, regarding these various 

 voluntary striped muscles of the tadpole, white mouse, gray mouse, 

 chicken, frog, and calf may be drawn. 



Ist — In the manner of termination of muscle fibres two general 

 types may be recognized, one in which the long axes of the tendon 

 and of the muscle fibres coincide, and the second in which they 

 meet at an angle. 



2nd — In neither of these two types are the muscle fibrillae 

 in continuity with the tendon fibrillae. 



3rd — Developing muscle fibres terminate in a number of cone- 



