486 PHYSIOLOGY CHAP. 



that the secretion of these glands is principally, if not exclusively, 

 the work of the cells in the coiled glands. The muscle-cells which 

 surround the basement membrane, and are interposed between it 

 and the epithelium, apparently serve by their contraction to 

 accelerate the flow of the secretion along the duct. 



Man has the capacity of sweating diffusely over the whole of 

 the surface of the skin, but perspires more easily and copiously 

 by the face, particularly the forehead, the palm of the hand, the 

 sole of the foot, the axilla, and the groins. The monkey sweats 

 more from the top of its nose, and very little from the palm of the 

 hand and sole of the foot, although these parts are hairless. The 

 horse and sheep sweat freely from all parts of the body, although 

 hairy ; the calf less readily ; the goat, rabbit, mouse, and rat not at 

 all. Carnivora, generally speaking, sweat only from the ball of 

 the foot, and even there the dog sweats little or not at all, while 

 the cat on the other hand (the chosen subject for physiological 

 investigation into sweat-secretion) perspires readily and copiously 

 in that part. The pig sweats almost incessantly at the flat 

 surface of the snout, where Gurtl found a large development of 

 sweat glands. In the ox the nasal pinnae (alae) are continually 

 moist with sweat. 



The power of sweating mainly or exclusively from certain 

 definite areas of the skin is in proportion not so much with the 

 number of sudoriferous glands in those regions and their total 

 absence in others, as with the varying secretory activity of these 

 glands. In fact, the coiled form of gland is not inseparably 

 associated with the function of sweating. There are highly 

 developed coiled glands which never secrete sweat during the 

 whole life-time. Such, e.g., are the glands existing in animals that 

 never sweat from any part of the skin, or those in regions where 

 sweat is never secreted. Obviously, these glands must have 

 another function, distinct from that of sweat secretion. We shall 

 see in effect that they probably have the same function as the 

 sebaceous glands. The coiled glands which abound in the skin of 

 the external auditory nieatus are a typical example of glands 

 which, with the complete structure of sudoriferous glands, have no 

 other office than that of secreting the cerumen which covers and 

 protects this passage. 



Krause (1844) made a laborious investigation of the dis- 

 tribution of the sweat glands in the different regions of the skin 

 in man, and determined the number that could be counted in a 

 square inch of surface. On reducing the unit of measurement to 

 square centimetres the results were approximately as follows : 



In the forehead . . . .140 



cheeks 60 



chest, abdomen, forearm . . 225 

 neck, back, rump 50 



