1879.] 



Dr. G. Thin. Anatomy of the Skin. 



253 



with half, per cent, chloride of gold solution. From time to time 

 different thicknesses of the fatty layer were removed as the solution 

 had had time to penetrate into the tissue, until finally the deeper layer 

 of the cutis proper was laid bare. The tissue, still extended, was then 

 placed in fresh gold solution for several hours. The object of the 

 manoeuvre was to secure the penetration of the fluid through the 

 bundles, whilst these were still extended in their natural condition. 



After a due action of the gold, the skin was cut into small pieces, 

 whicb were then treated by acetic and formic acids in various degrees 

 of dilution. Some of the portions were exposed to sunlight for several 

 days, in water feebly acidulated with acetic acid, and then the 

 strength of the acetic acid was raised to 20 per cent, of the ordinary 

 concentrated acetic acid of commerce. Other portions were treated 

 by formic acid. Some successful preparations were obtained from 

 portions macerated first for a few days in a mixture of one part formic 

 acicl, of specific gravity 1'020, and one of water, and then in the 

 undiluted acid for some days longer, but a strict adherence to these 

 strengths was not found necessary. 



Portions of the corium thus prepared were teased out in glycerine 

 and examined, directly or after staining by different dyes. Staining 

 by pikric acid I found very advantageous. 



I was able to isolate, in a condition favourable for study, the primary, 

 secondary, and tertiary bundles. Generally speaking, although not 

 invariably, the tertiary and secondary bundles were best seen in the 

 tissues macerated in acetic acid, and the secondary and primary 

 bundles in those treated by formic acid. 



Numerous elastic fibres were isolated by both methods, the finest 

 fibres more particularly in the formic acid preparations. These fibres 

 were frequently found only partially detached from the bundles, and 

 in such preparations the relations of the fibres to the bundles could be 

 well studied. The primary bundles isolated by these methods were 

 flattened, cylindrical elements, even contoured, homogeneous in appear- 

 ance, and uniform in breadth over the whole length isolated. The 

 difference in breadth between individual bundles was very slight. By 

 measurement, I found that they were from 0"004 to O'OOo millim. 

 broad. The primary bundles were sometimes seen in situ, that is to 

 say, as parts of a secondary bundle, the breadth of the latter being 

 normal. In other preparations the contours of secondary and tertiary 

 bundles were lost, and the microscopic field was filled with a large 

 number of primary bundles, entangled and twisted by the needles used 

 in teasing them out. Sometimes a number of primary bundles, 

 although separated from each other, were yet so placed that I could 

 feel assured that they were the constituent elements of one secondary 

 bundle. Such was the case Avith the primary bundles shown in 

 fig. 4. 



