Memoir on the Nature of fat Sidsta/ices. 37 



tain concrete substances very diffeient from true camphor, like 

 those which probably exist in the volatile oil of roses and in 

 that of the elder-tree which have the consistence of butter. We 

 may say the same of the volatile oils furnished by the umbelli- 

 ferous plants; such as the parsley, fennel, dill, cumin, and ani- 

 seed*, all of which have the property of freezing in a very slight 

 degree of cold. 



Expeiiments upon Suet. 



Physiologists are of opinion generally, that the fat has its seat 

 in the cellular texture. On examining witli the naked eye suet 

 as we meet with it in animals, i. e. that which envelops the kid- 

 neys in the ruminating quadrupeds, we find it arranged in con- 

 ciioid, square, or orbicular masses, separated from eacli other 

 by membranous laminie. If we examine each of these masses 

 attentively, we see them entirelv formed of an innumerable mul- 

 titude of oblong globuUs, transparent and brilliant like a crystal- 

 lized salt, and which seem tied to each other by a very loose 

 membranous texture, like the grains of starch in a boiled pota- 

 toe. We may separate these globules from each other by slightly 

 macerating the suet in cold water, and shaking the whole over a 

 hair sieve. Wq then obtain a powder which resembles starch 

 when it has been dried on gray paper. These membranous ve- 

 sicles containing the suet, did not appear to me to have the same 

 structure as the cellular texture, which is formed, as we know, 

 by the junction and mutual adlierence of the cellules whicli com- 

 municate with each other. 



In order to ascertain if those niembrauous cysts serving as a 

 reservoir to the fat had any oritices to allow it to escape, they 

 were exposed to different degrees of heat with water ; but it was 

 only at a heat of 65" of Reaunmr that some bubbles of greasy 

 matter melted, began to appear on the surface of the li(|Uor, 

 and even at the boiling point a great number of those isolated 

 vesicles still existed witiiout having given out any grease: hence 

 it follows that every globule of suet is contained exactly in a 

 membranous vesicular envelope,which hinders it from separating, 

 even at a heat much greater than that which is necessary for 

 melting it. The adipose glands of Malpighi, which no author 

 since his day has discovered, are they the same organs with 

 those vesicles filled with suet ? 1 am not inclined to think so, 

 since we observe the latter very distinctly without the assist- 



* On cx.'imiriiii"; some cai-ks wliicli li:irl contained aiiisi'cd oil, T tuund 

 tlie wliole iiisiiie frinj^td wi'.li a lirilli:iiii ilry crvstalliztd iDattvr, wliich it 

 was easy to c<illect, even in a considerable rjuantity ; and I tliou<ilit ot' ex- 

 amining tlicsc crystals more minutely: but liaving left them during a « hole 

 summer ex|)osed to tii«; solar li^lit, 1 found cheni resolved into u thick li- 

 quid which lost the I'aculty of ci-yttalliz!iig. 



C 3 ance 



