BY DR. KLEIN. 141 



the sectional surface, or by teasing. The tissue of the trabe- 

 culae, the special sheaths of the arteries, the stroma of the pulp, 

 and that of the Malpighian corpuscles, are best studied as fol- 

 lows : Small bits of fresh spleen are steeped in one or two per 

 cent, solution of bichromate of potash till they are fit for 

 making sections. The thin sections are then washed in water 

 (after coloring if desired), and carefully shaken in a test tube. 

 They are then covered in glycerin. In organs successfully in- 

 jected and prepared in the usual way, it can be made out that 

 the vascular S3 f stem is not definite!} 7 limited as in other tissues. 

 The circulating blood, before reaching the veins of the pulp, 

 passes through a system of channels without definite walls, 

 the so-called vasa serosa. 



CHAPTER XL 



SKIN, CUTANEOUS GLANDS, AND GENITO-URINARY 

 APPARATUS. 



SECTION I. SKIN.' 



Methods of Study. For the study of the structure of the 

 skin in general, the human integument is preferable to that of 

 the lower animals. Portions of skin with subcutaneous cellu- 

 lar tissue, obtained in as fresh a state as possible, are placed 

 in sherry -yellow solution of chromic acid, containing from one- 

 tenth to one-fourth per cent. After a week, or even sooner, 

 they should be transferred to common alcohol, and used for 

 the preparation of sections. As regards examination of the 

 epidermis, it is only necessary to add to the directions given 

 in Chapter II., that the best parts of the skin for the prepara- 

 tion of sections are the volar side of the fingers, the lips, the 

 alse of the nose, and the eyelids. Any part will answer equally 

 well for the investigation of the structure of the corium. If 

 it is desired to demonstrate the sweat glands, the palm of the 

 hand, the axilla, and after these the forehead, answer best. 

 Hairs can be examined in the skin of the scalp, the upper lip, 

 and eyelids. The sebaceous glands, whether those which open 

 into hair follicles, or those of which the orifices are free, can 

 be best prepared in the labia major a, prepuce, scrotum, or in- 

 ternal lining of the orifice of the nose or eyelid of new-born 

 children, and in the scalp of adults. The unstriped muscular 

 fibres of the skin, particularly the hairs, can be studied in the 

 scalp and scrotum, or in the skin which covers the anterior- 



