190 



EPITHELIAL GLOBULES. 



These epitheliums with vibratile cilia, which were first 

 studied in the lower animals by Hunter Sharpey and 

 Ehrenberg, have been since discovered in different mucous 

 coverings of the vertebrated animals, 

 and the mammifera. In the adult 

 man they are found in the nasal fos- 

 sae, the trachea, the large bronchi, the 

 eustachian tube, the membrana tym- 

 pani (the inner surface of the tympanic 

 membrane excepted) the nasal canal, 

 the deferent canals, the canal of the epi- 

 didymis, and the canals of the seminif- 

 erous cones; also in the Fallopian tube 

 and the uterus in woman. (Fig. 59.) 

 In the foetus they are also found in the 

 canal of the spinal cord, and the cere- Fig. 59. Ceils of the uterus 

 bral ventricles which follow it. 



In the other vertebrated animals 



,, ... ,. . -, , ,.,. 



the epitheliums are more widely dif- 

 fused, becoming still more numerous in the non-vertebrated 

 animals (the mollusks especially), in which they sometimes 

 line the whole external integument and the mucous membrane 

 of the digestive tract. 



Anatomie et 



Cellulaires." 



II. GENERAL PHYSIOLOGY OF THE EPITHELIUMS. LYMPHATIC 



SYSTEM. 



A. The epitheliums preside over the interchanges of nutri- 

 tion at their free surfaces. 



We have already seen in our general sketch of the organ- 

 ism that tine epitheliums manage the phenomena of inter- 

 changes with the outside, and that, in this respect, they are 

 divided into three classes: those which are impermeable, and 

 offer no passage either from the outside to the inside, or the 

 opposite ; those which allow a passage from the exterior to 

 the interior (absorption) ; and those in which, on the other 

 hand, the passage is from the interior to the exterior (se- 

 cretion). 



contrary to what is generally believed, was not perceptibly thinner 

 than in the autumn. In fact, the New England hunters say that 

 the amount of grease derived from these animals in the mouth of 

 May is very considerable, even if the preceding winter has been 

 long and severe. 



