245 



The author then proceeds to describe a tubular membranaceous 

 sheath, of the most exquisite delicacy and transparency, investing 

 each fasciculus from end to end, and isolating it from all other parts ; 

 this sheath he terms Harcolemma. Its existence and properties are 

 showTi by several modes of demonstration ; and among others, by a 

 specimen in which it is seen tilled with parasitic worms (Trichinse), 

 which have removed all the fibrillse. The adhesion of this sarco- 

 lemma to the outermost librillse is explained. 



It is also shown that there exist in all voluntary muscles a num- 

 ber of minute corpuscles of definite form, which appear to be identi- 

 cal with, or at least analogous to the nuclei of the cells from which 

 the development of the fasciculi has originally proceeded. These 

 are shown to be analogous to similar bodies in the muscles of or- 

 ganic life, and in other organic structures. 



The author next describes his observations on the mode of union 

 between tendon and muscle ; that is, on the extremities of the pri- 

 mitive fasciculi. He shows that in fish and insects the tendinous 

 fibrillse become sometimes directly continuous with the extremities 

 of the fasciculi, which are not taper, but have a perfect terminal 

 disc. In other cases the extremities are shown to be obliquely trun- 

 cated, where the fasciculi are attached to surfaces not at right angles 

 to their direction. 



Lastly. He states his opinion, and gives new facts on which it is 

 founded, that in muscular contraction the discs of the fasciculi be- 

 come approximated, flattened, and expanded ; the fasciculi, of course, 

 at the same time becoming shorter and thicker. He considers that 

 in all contractions these phenomena occur ; and he adduces argu- 

 ments to show the improbability of the existence of any rugae or 

 zigzags as a condition of contracting fasciculi in the living body. 

 The paper is abundantly illustrated by drawings of microscopic ap- 

 pearances. 



The Society then adjourned over the long vacation, to meet again 

 on the 19th of November next. 



