ON THE STRUCTURE OF TENDON. 133 



average^ for half an hour, and the process completed as 

 usual. 



When this method was quite successful, the specimens ob- 

 tained by it were exceedingly beautiful and highly instruc- 

 tive. The tendon bundles were found covered by alternate 

 rows of large cells, quadrilateral in shape, possessing a large 

 roundish nucleus usually terminally situated (see fig. 1), and a 

 bright nucleolus, and disposed, as I have said, on the surface 

 of the bundles, as was fully proved by the examination of 

 carefully teased specimens. When these were successfully 

 obtained, two or three isolated bundles were sometimes to be 

 found lying beside each other, but not actually in contact, on 

 which there was distinctly present a superficial cellular 

 covering, in one on the u^jper surface, in a second on the 

 under surface, and in a third bundle laterally disposed (that 

 is, seen in j^rofile as rows of thin oblong cells), while they 

 plainly bent around the bundle, that is, covered a larger area 

 than was indicated by their nucleus and the thickened pro- 

 toplasm surrounding it. 



A modification of the gold method is a combination of it 

 with the acetic acid one. The tendons are first slightly 

 swelled in a dilute acetic acid solution and then subjected to 

 the gold process as before. The results thus obtained agreed 

 exactly with those derived from the simple acetic acid pro- 

 cess, but the (appearances Avere more distinct, from the cells 

 being coloured of the usual purple. 



Individual tendons, after either the acetic acid or the com- 

 bined acetic acid and gold method, frequently exhibit a sheath 

 which in such preparations has an almost structureless ap- 

 pearance ; in it there are however found occasional fine longi- 

 tudinal lines, as if made by fibres. This sheath surrounds the 

 fibre bundles, and consequently corresponds in position to the 

 system of branched spaces which I have described as occur- 

 ring in the silver specimens, and which must be distributed 

 in the substance of the sheath. 



Specimens which will yield appearances in every respect 

 confirmatory of those already obtained, and in some respects 

 supplementary to them, may be made by combining the 

 silver and gold methods. The tendon is bathed in silver as 

 usual, after or without pencilling in serum, slightly washed 

 in water, and then transferred to the gold solution for fifteen 

 minutes ; the further preparation is not peculiar. 



In studying the structure of the tendons of the tail of the 

 adult rat, I again availed myself of the various methods of 

 preparation which I have described. Of these, I found it 

 was the silver process that yielded the most instructive spe- 



