392 MORBID ANATOMY OF THE SKIN. 



strikingly passive in all disorders due to retention. At first it 

 acts merely as a plug to complete the closure of the follicular 

 orifice. The greater the subsequent accumulation of epidermic 

 masses, the more does the middle part of the hair waste ; its 

 o-rowth is either whollv arrested, or continues for a while in a 

 meaffi'e sort of way. 



§ 334. Before leaving the present subject, some allusion 

 ought to be made to a phenomenon, which is peculiarly frequent 

 in association with atheromatous cysts, but which also possesses 

 a certain degree of general interest in reference to the pathology 

 of the hair-sac : I refer to its displacement. 



The normal hair-sac — so at least we are taught by normal 

 histology — is embedded in the substance of the true skin ; it is 

 only the longest and most vigorous hairs which push their roots 

 into the subcutaneous adipose tissue. This statement needs 

 qualification. It is true that in a cross-section through the 

 healthy skin, the great majority of the hair-sacs really do not 

 extend beyond the limit of the cutis. No sooner however is the 

 hair-sac enlarged to any considerable extent, than it forces its 

 way out of the cutis and becomes subcutaneous. Accordingly 

 even the smaller atheromatous cysts are all situated, not in the 

 substance of the cutis, but underneath it. We observe a pre- 

 cisely analogous displacement of the follicle in Iujdus, in hyper- 

 trophy of the sebaceous glands, &c., so that its cause is really 

 worth inquiring into. And here an old observation of my own, 

 which I made during the investigation of a colossal myxoma 

 (twelve pounds in weight) from the skin of the back, comes 

 in very appropriately. 



This tumour had originated in the subcutaneous areolar 

 tissue ; the skin over it was very tightly stretched. On removing 

 any part of this cutaneous investment and examining its under 

 surface with a powerful lens, it became at once apparent that 

 the hair-sacs with their appended sebaceous glands were pro- 

 jecting from it. Some were quite free ; others lay in shallow, 

 funnel-shaped depressions, formed by the dissociation of the 

 fasciculi of the dermal connective tissue. The general im- 

 pression conveyed was, that pre-existing recesses had been 

 opened up from below by the stretching to which the skin was 

 exposed, just as the mouths of the uterine glands become funnel- 

 shaped when the mucous lining of the organ is distended from 



