SECTION OF SKIX. 



677 



puscles, when floating in their own serum, or after having 

 been treated with acetic acid or water, appear to be fur- 

 nished w^th perfectly plain coverings, composed of a simple 

 homogeneous membrane, without distinction of parts. But, 

 when the blood is treated with a solution of magenta (nitrate 

 of rosanilin) or with a dilute solution of tannin, the cor- 

 puscles present changes which seem irreconcileable with 

 such a proposition. Dr. W. Eoberts, of Manchester, com- 

 municated an account of his observations on this subject to 



Fig. 313. — A vertical section of the Human Skin, showing the sweat-glands, sur- 

 rounded by fat-globules, the ducts passing upwards through the epithelial 

 layer to the epidermis or external cuticle, uiagnilied 250 diameters. 



the Eoyal Society (Proc. Boi/. Soc. vol. xii. p. 481), in 

 which he shows that nearly every disc possessed a parietal 

 macula, capable of being stained by a dye. It was com- 

 monly of a lenticular shape, but sometimes square, and as 

 a rule very minute, not covering more than l-20th or l-30th 

 of the circumference. Moreover, in the blood of many of 



