288 J. S. FERGUSON 



Again in the fibrous perichondrium of hyaline cartilage, as 

 Studnicka ('06) has pointed out, there is a considerable layer of 

 l:lackened fibers marking the border of the cartilage and in the 

 younger tj'pes extending into its matrix; the outer layers of the 

 perichondrium are clearly, however, collaginous tissue, and in 

 my preparations present the characteristic golden brown color, 

 sharply distinguished from the intense black of the argentiferous 

 fibers. The matrix of the cartilage in the same sections retains 

 a brownish tint except in the younger specimens and at the margins 

 of the cartilaginous plates in the more mature cases. The black- 

 ening of the innermost fibers of the perichondrium which mark 

 the "growing surface" of the cartilage may be explained by the 

 increased affinity for silver shown by the fibers of young connec- 

 tive tissue as compared with the mature, a relation which I am 

 not ready to discuss further at this time. 



The remarkable differences in reaction to the impregnation in 

 many of the mature tissues, especially such as contain typical 

 reticulum, would tend to refute the German idea of the identity of 

 collaginous and reticular tissue and to confirm the opinion of Mall 

 that reticular tissue or "reticulum" is a distinct entity, though this 

 latter contention cannot yet be established from the standpoint 

 of the method here used until it is viewed in the light of the his- 

 togenesis of the connective tissues, for there the sharp lines of 

 demarcation diminish even to the vanishing point. 



Such characteristic differences between reticulum and collag- 

 inous fibers as may be observed at almost any point in thin sec- 

 tions of the lymphoid tissues impregnated by silver leave little 

 to be desired in the way of morphological differentiation of these 

 two types of fibers. Such areas are well and accurately shown in 

 fig. 5, from the lymphatic gland of man, and fig. 6 from the margin 

 of a Peyer's patch in the human intestine. One feels, therefore, 

 that the separate and distinct character of collaginous and retic- 

 ular fit)rils in the mature tissues as shown by silver impregnations, 

 fortified as it is by the chemical differences demonstrated by Sieg- 

 fried and Mall, the one, collaginous, yielding gelatin, the other 

 yielding a "reticulin" presenting different chemical reactions, 

 forms at least a satisfactory working basis for the further study 



