10 DR. G. THIN. 



It will be seen from the drawing that the silver is depo- 

 sited in a connected series of black curves and circles, and when 

 the deposit is not too abundant it can be observed that the 

 ordinary cartilage-cells are mostly found in the area of the 

 deposit. This is still better seen in preparations like that 

 represented in Fig. 7. This drawing represents a section 

 through the cartilage of the knee of a frog that died from 

 disease. The section was placed in a silver solution, and as 

 is shown in the drawing a large part of it was covered with 

 a network of silver deposit. Where the net'work Avas com- 

 plete it was found that the encircled ground-substance was 

 stained a faint brown and that no cells Avere visible. That 

 the cells were in line with and covered by the deposit was 

 shown by an examination of the edge of the area of deposit 

 where it was incomplete. 



At this part the position of the cells was indicated some- 

 times by a white unstained circle, and sometimes by a similar 

 circle partly filled by the silver precipitate. It is evident, 

 then, that the precipitate takes place most easily in the circular 

 spaces, and afterwards in curved tracts of tolerably uniform 

 breadth which connect the spaces. 



A general or unsystematic precipitate of silver in such pre- 

 parations was never observed, nor was there ever a departure 

 from the usual type either in the size of the meshes of the net- 

 work or in the breadth of the tracts of which it is composed. 



The similarity between this network and that of the 

 lymphatic capillaries which are indicated by silver deposit 

 in the perichondrium is evident. 



Metallic deposit in silver preparations is sometimes found 

 in a different relative position. In that part of the articular 

 cartilage which is near the bone the ground-substance has, 

 as is well known, a peculiar arrangement. The cavities or 

 depressions known as capsules appear much larger, and the 

 intermediate substance assumes somewhat the character of a 

 framework, arranged in parallel beams, which are connected 

 by transversely disposed arches. The metallic precipitate at 

 this part of the cartilage is frequently found deposited in the 

 centre of the beams and arches, whilst the contained cellular 

 spaces may be free from it. 



In preparations of this kind, in which a small portion of 

 bony substance has been removed in continuity with the 

 cartilage, I have been able to trace the continuity of the tracts 

 of deposit with similar tracts in the bone, a fact of which the 

 sio-nificance in relation to the nutrition of cartilage is 

 sufficiently evident- This form of metallic deposit is shown 

 in Fig. 9. 



