THE SWEAT. 385 



We have at present no means of determining the quantity of 

 matter secreted by the sebaceous glands collectively, or by special 

 groups of them ; moreover, daily experience teaches us that the 

 amount must be very variable in different individuals and under 

 different physiological and pathological conditions. 



With regard to the origin of this secretion, we must bear in 

 mind (when further investigating it) that the fat of the sebaceous 

 glands must either be derived directly from the blood of the capil- 

 laries coiling around them, or must be formed from other matters 

 in the cells of these minute glands ; for it is worthy of notice that 

 almost all these sebaceous glands are, as it were, rooted in a tissue 

 which is completely devoid of fat, and do not penetrate into the 

 fatty cellular tissue beneath the corium ; the glans penis is almost 

 absolutely devoid of fat. The variously refracting granules, 

 globules, and vesicles which occur in many cells, as, for instance, 

 in those of the external auditory canal and of the Meibomian 

 glands, so frequently appear to represent new progressive stages 

 of development of the same object, that we are almost led to the 

 conjecture that the fat peculiar to these secretions is primarily 

 formed within these glands. 



These glands yield a fatty investment to the hair and cuticle ; 

 Krause* regards it as definitely established that this secretion 

 diminishes the hygroscopical property of the horny layer of epi- 

 dermis and of the hair, and that it hence checks the too rapid 

 evaporation of moisture, and the drying up of the deeper epidermic 

 layers and of the corium. 



Under the term sweat we include only the fluid secretion of 

 the sudoriparous glands, without reference to the question, whether 

 these glands are also the sources of the gaseous transpiration of 

 the skin or not. The sudoriparous glands are thread-like, delicate, 

 single tubes, not communicating with one another, which originate 

 in a blind extremity in the fatty subcutaneous cellular tissue, where 

 they form spirally twisted coils ; they then make their way through 

 the corium and the younger epidermic layers in a corkscrew-like 

 or serpentine course, and finally open with a considerably con- 

 tracted mouth in the cuticle. These tubular sudoriparous glands 

 are always invested with an epithelium which consists of roundish 

 or oval-angular nucleated cells. 



The sweat, as it collects in drops upon the skin of a person 

 who is perspiring freely, is, as is well known, a colourless, very 

 watery fluid, with a rather saltish taste, and usually communicates a 



* Handworterb. de Physiol. Ed. 2, S. 135. 

 VOL. II. 2 C 



