364 THE SECRETIONS: 



contains urea as well as allantoin is a point not yet ascer- 

 tained. 1 



In speaking of the liquor amnii we mentioned that the 

 floccules which are seen swimming in it are derived from the 

 peculiar caseous matter, the vernix caseosa, which invests the 

 foetus. I shall avail myself of this opportunity of offering 

 a few remarks upon this substance. Upon examining this ca- 

 seous investment with the microscope, I found, especially when 

 it had been previously diluted with water, a very large quantity 

 of pavement epithelium, numerous fat-vesicles, and some but 

 not a great many crystals, which in part resembled cholesterin, 

 and in part distinctly assumed the form of ammoniaco-magne- 

 sian phosphate. 



Upon examining the vernix caseosa by the microscope, with- 

 out previously diluting it with water, indications of a large 

 number of crystals presented themselves; they disappeared, 

 however, on the addition of water, and I concluded that this 

 peculiar appearance was caused by epithelium-cells. 



According to Fromherz and Gugert the vernix caseosa con- 

 sists of a mixture of fat resembling cholesterin with coagulated 

 albumen. Microscopic investigation at once shows that what 

 was considered by these observers as albumen, was at any rate 

 for the most part epithelium, and that a considerable quantity 

 of fluid fat must be present besides cholesterin. They also 

 state that ether takes up from the vernix caseosa a fat which 

 crystallizes in glittering leaves, which does not admit of sapo- 

 nification, and does not melt in boiling water. Cold water 

 takes up a little of the portion which is insoluble in ether, and 

 boiling water takes up a yellowish substance with an alkaline 

 reaction, which they regarded as ptyalin, but which Berzelius 

 conceives to be most likely albuminate of soda. The residue 

 is evidently epithelium, since it is insoluble in a cold, but 

 soluble in a boiling solution of potash. 



[The most recent observations on the vernix caseosa are those 

 of Dr. Davy. 2 He states ' ( that its specific gravity (after the 

 air that is entangled in it is removed) is 1003-9. It is very 



1 See vol. I, p 57. a Medico-chir. Trans. 1844, p. 193. 



