24 i)K. !ji:am;_, on thi; tis.sues. 



tissue. Tlic soft living inateriiil is, of course, easily dc- 

 stroyetl, soon decays after deatii and leaves spaces and tubes, 

 but during life these are occupied Avith the only matter of 

 the tissue which can produce new matter, the material on 

 which the growth, the nutrition, in short, the life of the 

 whole depends. 



In pathological alterations the germinal matter of cuticle 

 or of cartilage will undergo multiplication in precisely the 

 same manner as the germinal matter of a tissue, the several 

 masses of which commtmicate witli each other by tubes. 



It has been shown that in some tissues, as cartilage, the 

 masses of germinal matter ai-e entirely separated from each 

 other by formed material, while in others, as tendon, they are 

 continuous. Gradually, however, these channels of commu- 

 nication in many tissues become completely closed up, 

 although their position continues to be marked by a line 

 exhibiting a different amount of refractive power to the rest 

 of the formed material. How is this fact to be accounted 

 for on the supposition that these are mere tubes for the 

 transmission of nutrient fluids ? 



In tissues Avhich are rendered impermeable by the precipi- 

 tation of calcareous matter in the formed material, and 

 which are at the same time quickly produced and quickhr 

 removed, channels must exist for the transmission of 

 fluids to and from the germinal matter. But in soft, 

 permeable textures such tubes are not required as fluids 

 circulate freely through the interstices of the tissue or formed 

 material. 



These corpuscles and commmiicating tubes "\>hich arc 

 regarded by Yirehow as belonging to an extensive nutrient 

 system of tubes and cavities, exhibit very different characters 

 in closely allied tissues. Although present in periosteum and 

 perichondrium, they are absent in permanent and temporary 

 cartilage. The bundles of white fibrous tissue contain, it is 

 admitted, a vast number of them, while the substance of the 

 elementary fibre of muscle iu immediate continuity with the 

 tendon is, at least in many instances, destitute of anything 

 like such an arrangement ; although the first tissue is one in 

 which the nutritive changes are slight, while in the latter 

 they are admitted to be very active. 



The mucous tissue of the cord, according to Yirehow, 

 consists almost entirely of these anastomosing tubes, and 

 there a most elaborate system for the conveyance of nutrient 

 juices is said to exist, although Avitli the exception of a little 

 imperfectly formed fibrous tissue and viscid matter there 

 appears nothing in this texture requiring nourishment. 



