BIOPLASM OF MUSCLE. 225 



for comparison. Such a specimen will, I think, con- 

 vince any one that the masses of bioplasm are con- 

 cerned in the production of the contractile material 

 of muscle. By the accurate comparison of carefully 

 prepared specimens of this kind, we are even able to 

 form a notion of the rate of the growth, and to prove 

 that muscular tissue is not formed very quickly, or 

 its elements removed and replaced within a short 

 period of time. It is not improbable that in the 

 higher vertebrata the very same elementary fibres 

 continue in action for years. The idea that the con- 

 tractile material is removed and replaced by new 

 tissue within a few days or weeks is untenable, and 

 would not have been suggested by any one who had 

 taken the pains to acquaint himself with well-known 

 facts, unless he or had determined to ignore the results 

 of anatomical observation altogether. 



From what I have already stated, the reader will 

 have inferred that the position of the masses of 

 bioplasm varies very much in different kinds of striped 

 muscle. In some forms we find a row of nearly 

 spherical bioplasts in the very centre of the elementary 

 fasciculus of contractile tissue : in others an oval 

 mass is seen at the side of a very long narrow fibre 

 consisting of very few fibrillae ; and in many of the 

 muscular fibres of various classes of vertebrata nu- 

 merous oval masses are situated at short distances, and 

 alternating with one another throughout the whole 

 extent of the tissue within the sarcolemma. This 

 variation in position, and the difference observed in 

 the relative proportion of bioplasm and contractile 

 tissue in muscles which act in the same manner, lead 

 me to infer that the bioplasm is not immediately con- 

 cerned in muscular contraction. 



The living matter is instrumental in the formation 

 of the original contractile tissue, and in the produc- 

 tion of new tissue to take the place of that which is 

 slowly removed, or to be added to that which exists 



Q 



