FORMATION OF FIBEOUS CONNECTIVE IN GLANDS. 103 



bioplasTii, situated most externally, only produce con- 

 nective tissue, and the muscle itself results from the 

 development of those occupying a more central 

 situation. The same fact is noticed in the develop- 

 ment of nerve fibres. The masses of bioplasm, 

 situated at the outer part of the bundle, do not pro- 

 duce true nerve fibres, but from them is formed con- 

 nective tissue only. Up to a certain period the 

 formation of true nerve fibres may have been possible, 

 but a sufficient number of perfect fibres having been 

 developed within, the marginal fibres degenerated and 

 took the low form of fibrous connective. 



151. Formation of fibrous coiineetive in inlands. — 

 But the natui'e of this connective, and the mode of its 

 production, are very conclusively determined by in- 

 vestigating the changes which occur during the de- 

 velopment of a gland of highly complex structure, 

 like the kidney or liver of man and the higher 

 animals. At an early period of development the 

 cells concerned in the formation of the kidney, for 

 instance, multiply and become arranged so as to form 

 a cylindrical mass. By their division and subdivision 

 this inci'eases in length and circumference, at least 

 during a certain period, in every part of its extent. 

 At the deep or external portion of these cells, adjacent 

 to the vessels, matter is slowly deposited in an in- 

 soluble form, and thus a thin membranous boundary 

 corresponding to the outer limit of the future tube 

 results, and this becomes extended as the cells grow, 

 while at the same time it is increased in strength by 

 the addition of new matter. Between the lines of 

 masses of bioplasm from which the tubes are de- 

 veloped, and those which take part in the formation 

 of vessels and nerves, are a few masses which are not 

 concerned in the formation of any definite structure, 

 but which perhaps take part in the production of a 

 small quantity of intervening substance. The mem- 

 brane becomes further modified by its relation to the 



