VER1OX CASEOSA. % 67 



near the end of gestation is generally covered with a whitish 

 coating, or srnegma, called the vernix caseosa. This is most 

 abundant in the folds of the skin ; but it generally 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 ca- 

 seosa. 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 ; l and we can form 

 the best idea of its constitution and mode of formation from 

 microscopical examination. 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 microscopi- 

 cal examination, to consist of an immense number of epithe- 

 lial cells, with a very few small fatty granules. In the table 

 given below it will be seen that these cells, after desiccation, 

 constituted about ten per cent, of the whole 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. 



1 The following table gives an approximative idea of the nature and quan- 

 tity of the various substances that have been found in the vernix caseosa. 

 This table was arranged by Robin from analyses by different observers : 



Composition of the Vernix Caseosa. 



Water 769'80 to 778'70 



Nitrogenized matter, mucous or caseous 4-50 



Desiccated epithelium 101 '30 



Cholesterine, . } 



Oleine and margarine, > IOS'25 



Oleates and margarates of potassa and of soda, ) 



Chloride of sodium, *| 



Hydrochlorate of ammonia, t .._ 



Phosphate of soda and of lime, [ ' 



Ammonio-magnesian phosphate, J 



ROBIN, Lemons sur Us humeurs, Paris, 1867 p. 590. 



