80 C. F. MAESHALL. 



centripetally ; and that the special characters of the adult cell 

 appear first aud are most marked at the periphery, i. e. farthest 

 from the nucleus. Examples of this rule are seen in the de- 

 velopment of epidermic- cells, dentine, cartilage, and bone. In 

 bone and dentine the processes are not supposed to grow from 

 the cells, but to be formed by the lengthening of connecting 

 strands by deposit of new matter. 



Secondly, the nerve-ending being on the surface of the fibre, 

 and the network also appearing first on the surface, the con- 

 nection between the two can be established from the first; 

 whereas if the network grew out from the nuclei it could only 

 be connected with the nerve-ending at a much later period. 

 Hence the fibre would be useless till it was far advanced in 

 development, because for the network to be of any use it must 

 from the first be connected with the nerve-ending. For a new 

 structure of any kind to be developed it must always have been 

 of use from the first, either for its ultimate purpose or for 

 some other. If the network grew out from the nuclei it 

 could not be of use till it got to the nerve-ending, i. e. to the 

 surface. 



In considering this point we may imagine that the cell 

 divides into " formed and unformed matter " (Beale), the 

 formed matter being characteristic of the particular cell. In 

 the case of the muscle-fibre the protoplasm divides into net- 

 work and muscle-plasma all along, beginning at the periphery 

 and gradually extending to the nucleus. We are here met by 

 an apparent difficulty, for in the muscle-fibre the "formed 

 matter " which is characteristic of the cell is the muscle- 

 plasma, and not the network (which is presumed to be the 

 contractile part). But the special feature of striped muscle is 

 not the fact that it contracts, but the mode in which this is 

 brought about, i.e. the rapidity; and this will be a matter of 

 nutrition which will depend on the muscle-plasma. There- 

 fore the special feature of striped muscle is probably the mode 

 of nutrition of its specially contractile part, i. e. quick repair. 

 The active network bathed in such a fluid is placed in a good 

 position for such rapidity. 



