ON THE STRUCTUllE OF HYALINE CARTILAGE. 9 



tion. The cartilage was then cut in thin sections more or less 

 perpendicularly to the long axis of the bone, the sections 

 being placed as they were cut in glycerine. They were then 

 exposed to sunlight, and after a few hours examined. In 

 some of the sections the ground-substance was found to be 

 impregnated a dark brown in the form of uniform parallel 

 straight bands or ribbons about the breadth of the diameter 

 of a human red blood-corpuscle, which were separated by 

 white (unstained) lines of a quarter to half the breadth. The 

 alternation of the broader brown and narrower Avhite lines 

 is of the most regular kind. At the spaces which indicate 

 the position of the ordinary cartilage- cells these bands are 

 interrupted. 



The part of the cartilage next the bone shows them most 

 frequently. They are found, however, in all j^arts of the 

 cartilage except the most superficial layers, but this may be 

 accounted for by proximity to the directly cauterized surface. 

 From sections of the condyles of three kittens so treated and 

 examined about a score of available preparations were 

 obtained, and as they are still (after about four months) 

 good it is hoped they may be permanent. 



Opportunity was Avanting to extend this series of observa- 

 tions to other mammals, but two similar preparations were 

 obtained and preserved from the cartilage of the head of the 

 femur of the frog. As they differ in no respect from those 

 seen in the kitten's cartilage, except in so much as the white 

 lines were relativelj^ broader, no drawing of them has been 

 given. No attempt has been made in the figure to imitate 

 the colour of the brown staining, and the lines are more 

 wavy than they are generally seen. Otherwise the repre- 

 sentation is accurate. Only a fraction of a jDreparation so 

 marked has been drawn, the extent of surface showing this 

 peculiar impregnation being in many of the preparations very 

 much larger than that shown in the figure. The interjireta- 

 tion of this appearance will find its place further on. 



In some silver preparations there is a more or less abund- 

 ant deposit in the substance of the cartilage, and in every 

 instance the form in which the deposited substance is seen may 

 be placed under one of two types. One of these types is 

 shown in Figs. 7 and 8, and the other in Fig. 9. Pre- 

 parations like that copied in Fig. 8 are obtained either by 

 rubbing over the surface of the cartilage with the solid nitrate 

 or by placing sections in the silver solution. What the con- 

 ditions are that produce this appearance, and not the others 

 previously described as being sometimes obtained by a 

 similar procedure, have not been determined, 



