DR. BEALEj ON THE TISSUES. 247 



greatest encouragement to continue the same course of in- 

 vestigation. 



Changes occurring as elementary parts grow. — If we ex- 

 amine the elementary parts near the vascular surface of the 

 skin^ or a mucous membrane, we shall have no difficulty in 

 convincing ourselves of the following facts : 



1. That they are much smaller than those near the sur- 

 face. 



2. That, although very small, the proportion of the ger- 

 minal matter to the formed material is very much greater 

 than in the older elementary parts. 



3. That the formed material gradually increases as the 

 elementary part grows towards maturity, the germinal matter 

 absolutely increasing; but in proportion to the formed material 

 it is relatively diminished. 



After the elementary part has reached maturity, and has 

 advanced some distance from the vascular surface, where it 

 commenced its existence, the outer part of the formed material 

 perhaps shrinks and becomes harder and drier, while the 

 germinal matter gradually undergoes conversion into new 

 formed material, until the proportion becomes very small, 

 and the remainder, now at a long distance from the vascular 

 surface, and separated from any nutrient matter by a hard, 

 dry mass of formed material, as, for instance, in the cuticle, 

 dies. 



Specimen No. 17 showed a portion of the epithelial cover- 

 ing of a papilla from the tongue of a girl aged ten years. 

 This is to illustrate the growth of the epithelium. The 

 deepest layer consists of masses of germinal matter separated 

 from each other by a very thin layer of formed material, 

 which is not coloured by the carmine. These are for the 

 most part spherical or oval, some are undergoing division into 

 two. The formed material of the deepest series is seen to be 

 continuous with the formed material of the dermic structure. 

 At the outer part elementary parts are seen which occupy as 

 much space as six or eight of the youngest ones. Each con- 

 tains a dark-red mass of germinal matter, larger than that of 

 the youngest particles, but bearing a proportion to the entire 

 elementary part considerably less than that belonging to the 

 youngest particles. It is, therefore, clear that in the growth 

 of these elementary parts the germinal matter and the formed 

 material have both increased. The whole of the nutrient 

 matter absorbed has passed through the stage of germinal 

 matter, and become formed material which has gradually 

 accumulated. The oldest elementary parts are removed from 

 the specimen, but the proportion of germinal matter gradu- 



VOL. I. NEW SER. S 



