538 APPENDIX. 



would deny the existence of ciliary processes on the cells of 

 this epithelium. 



The Pacchionian Glands. 



The Pacchionian Glands are found among the vessels of 

 the pia mater on the edges of the cerebral hemispheres, and 

 are described as granulations composed of an albuminous 

 material ; they push before them the arachnoid membrane, 

 project into the longitudinal sinus, and, in some cases, even 

 occasion absorption of the parietal bones, lying imbedded in 

 little pits or recesses. They are stated not to occur in early 

 life, and they are frequently absent in the adult. 



I have encountered on the surface of different portions of 

 the pia mater, usually near to the sulci of the convolutions, 

 little masses or bodies of two forms, apparently very distinct ; 

 in the first, these were opaque and whitish, and consisted of 

 a capsule of fibrous tissue, enclosing a number of minute 

 granular cells ; in the second, the masses appeared to lie free 

 amongst the vessels of the pia mater, and each broke up 

 readily on being touched into several other smaller granula- 

 tions of the same character : these examined with the micro- 

 scope, were seen to be made up of numerous dark looking 

 bodies very irregular in form and size, and which appeared 

 to be of a fatty nature. 



Observations on the Development of the Fat Vesicle* 



" WHEN the difficulty of determining the exact structure of 

 the fat vesicle is considered, a difficulty arising from the 

 extreme tenuity of its cell-wall, and the opacity of its con- 

 tents, it is scarcely surprising that we should yet be with- 

 out any consistent account of the modes of development and 

 growth of the fat vesicle. 



* By the Author. " Lancet," January 20th, 1849. 



