462 GEORGE A. BAITSELL 



may be entirely lacking. This raises at once the question as to 

 how such a material is governed. Heidenhain believes^* that 

 "den Intercellularsubstanzen jene eigenartige Automatie des 

 Lebens zukommt, welche alle lebenden Telle besitzen." He also 

 holds that there is an external regulation of some sort but "Woher 

 diese Regulation stammt, ist uns einstweilen verborgen." 



A consideration of the intracellular theory as modified by the 

 studies of Hansen and Mall and the intercellular theory reveals 

 a quite close agreement. This rests upon the recognition in 

 both theories that a common intercellular ground substance is 

 present in which fibers form independently of cells. The differ- 

 ence between the two theories lies in the question of the nature 

 of the intercellular ground substance; the intercellular theory 

 holding that it is a secretion product of the embryonic cells and 

 the Hansen-Mall theory holding that it is a special type of living 

 matter formed by a syncytium of the mesenchyme cells. 



In this connection, the present researches give evidence that 

 the ground substance is nothing more than a type of secretion 

 given off by the embryonic cells. This conclusion is based, 

 first, upon the fact that ground substance is formed originally 

 before any syncytium of mesenchyme cells could have been 

 formed and, second, that material which has been properly 

 stained with JMallory's connective tissue stain shows, at all stages, 

 a clear and consistent differentiation in the color reaction between 

 cell cytoplasm and the ground substance. 



The ground substance having been formed, the next step we 

 have to consider is the formation of the connective tissue fibers. 

 In this connection from the intracellular standpoint, Flemming 

 and others have clearly demonstrated that the cells in developing 

 connective tissue contain intracellular fibers which they regard 

 as being connective tissue fibers. The presence at times of these 

 intracellular fibrillar structures cannot be questioned but con- 

 clusive proof is lacking that they become the connective tissue 

 fibers; there is the possibility that they are transient fibrillations 

 due to various factors, examples of which can be found in many 

 types of cells. 



•* Heidenhain, 1907, p. 48. 



