60 THE EXTERNAL AND MIDDLE EAR, BY J. KESSEL. 



well as their form and contents, justifies us in considering tliat 

 they belong to the lymphatic system. . 



I have in vain sought, in works devoted to this subject, for any 

 statements relating to the lymphatics of the tympanic cavity. Prussak 

 (37), who investigated the minute anatomy of these parts in the Dog, 

 denied their existence altogether. He maintained that, owing not 

 only to the mode of formation of the numerous large veins from 

 capillary plexuses, but to the direct connections between small arteries 

 and veins, and to the passing away of large veins at various points, 

 the circulation is carried on under a low pressure, and with great 

 rapidity, by no means favouring exsudations which might have been 

 expected to occur on account both of the loose nature of the soft parts 

 separating the bloodvessels from the tympanic cavity, and of the 

 absence of lymphatics. Now, although the arrangements in the blood 

 vascular system of the mucous membrane in the Dog, described by 

 Prussak, may be admitted to exist, we must nevertheless here also 

 seek, in the presence of lymphatics, the principal reason for the non- 

 occurrence of such pathological results ; and indeed it may easily be 

 demonstrated that the absorbing surface of the lymphatics exceeds 

 collectively that of the bloodvessels. From the position the 

 lymphatics occupy in the -above-described system of cavities, imme- 

 diately beneath the thin elastic, but easily compressible membranes, we 

 may admit in these cases, besides the ordinary causes effecting the 

 movement of the lymph, the frequent alterations of pressure occurring 

 in the tympanic cavity, since these appear, together with the above- 

 given mechanical arrangements of the lymphatic system, to be well 

 adapted to exercise, sometimes a suction power on the contents of the 

 tympanic cavity, and sometimes a pressure forcing them forward. 

 The statements of Voltolini (46), that a small quantity of clear fluid is 

 constantly present in the tympanic cavity of Man, I can only cor- 

 roborate in the case of the mastoid cells. 



Peculiar cells still require to be noticed, which for the most 

 part lie between the bloodvessels and lymphatics of the deep- 

 est layers of the periosteum of the bulla ossea, but are also 

 distributed through the more superficial stratum of connective 

 tissue as far as to the epithelium. In the corpuscles themselves 

 may be distinguished a discoid or more spherical or oval body 

 and several processes. The body of the cell usually exhibits a 

 large vesicular nucleus with a distinct nucleolus, or sometimes 



