VEKNIX CASEOSA. 363 



of a whitish, grumous matter, of a cheesy consistence, is sometimes found, particularly 

 when proper attention is not paid to cleanliness. The matter which thus collects in 

 the folds of the prepuce has really little analogy with the ordinary sebaceous secretion. 

 Examination with the microscope shows that it is composed almost entirely of irregular 

 scales of pavement-epithelium, which do not present the fatty granules and globules usu- 

 ally observed in the cells derived from the sebaceous glands. Robin regards the produc- 

 tion of this substance as entirely independent of the secretion of sebaceous matter, as it 

 is formed chiefly in parts of the prepuce in which the sebaceous glands are wanting. 



The smegma of the labia minora is of the same character as the smegma preputiale ; 

 but it contains drops of oil and the other products of the sebaceous glands found in these 

 parts. 



Vernix Caseosa.The surface of the foetus at birth and near the end of gestation is 

 generally covered with a whitish coating, or smegma, called the vernix caseosa. This is 

 most abundant in the folds of the skin ; but it usually covers the entire surface with a 

 coating of greater or less thickness and of about the consistence of lard. There are 

 great differences in foetuses at term as regards the quantity of the vernix caseosa. In 

 some the coating is so slight that it would not be observed unless on close inspection. 

 There are few analyses giving an accurate view of the ultimate composition of this 

 substance ; and we can form the best idea of its constitution and mode of formation from 

 microscopical examinations. If a small quantity be scraped from the surface and be spread 

 out upon a glass slide with a little glycerine and water, it will be found, on microscopical 

 ex 'lation, to consist of an immense number of epithelial cells, with a very few small, 

 fa v granules. In the following table, it is seen that these cells, after desiccation, con- 

 stituted about ten per cent, of the entire mass. The fatty granulations are very few and 

 do not seem to be necessary constituents of the vernix, as they are of the sebaceous mat- 

 ter. In fact, the vernix caseosa must be regarded as the residue of the secretion of the 

 sebaceous glands, rather than an accumulation of true sebaceous matter. 



Composition of the Vernix Caseosa. (Robin.) 



Water 769-80 to 778-70 



Nitrogcnized matter, mucous or caseous , 4'50 



Desiccated epithelium 101'30 



Cholesterine, \ 



Oleine and margarine, \ 108'25 



Oleates and margarates of potassa and of soda, ) 



Chloride of sodium, ^ 



Hydrochlorate of ammonia, 14-9* 



Phosphate of soda and of lime, f ' 



Ammonio-magnesian phosphate, ) 



The function of the vernix caseosa is undoubtedly protective. If we attempt to make 

 a microscopical preparation of the cells with water, it becomes evident that the coat- 

 ing is penetrated by the liquid with very great difficulty, even when mixed with it as 

 thoroughly as possible. Indeed, we never observe at birth the peculiar effects of pro- 

 longed contact of the cutaneous surface with water. The protecting coat of vernix caseosa 

 allows the skin to perform its functions in utero, and, at birth, when this coating is 

 removed, the surface is found in a condition perfectly adapted to extra-uterine existence. 

 It is not probable that the vernix caseosa is necessary to facilitate the p.'iss.-iL'v of the child 

 into the world, for the parts of the mother are always sufficiently lubricated with mucous 

 secretion. 



Cerumen. A peculiar substance of a waxy consistence is secreted by the glands that 

 have been described in the external meatus, under the name of ceruminous glands, mixed 



