10 THE HISTOGENESIS AND GROWTH OF THE OTIC CAPSULE AND ITS 



HISTORICAL. 



The first monographic treatise on the anatomy and physiology of the ear was 

 that published by Breschet in 1833. This work proved to be a very important one , 

 both as regards the new observations contained in it and the constructive manner in 

 which the facts then known were analyzed. The terminology of the ear region was 

 standardized and most of the names that were used or introduced by Breschet are in 

 use in the literature of to-day. Before stating his views concerning the structures 

 with which we are dealing, reference must be made to the work of some of his prede- 

 cessors, and this will be given essentially as outlined by him. 



The early anatomists were familiar with the bony labyrinth, but supposed that 

 the spaces contained within it were filled with air. In 1707, however, Valsalva 

 described the normal presence of a fluid in the labyrinth which he compared to the 

 fluid seen in serous cavities. The presence of this fluid was confirmed by Vieussens 

 (1714). His observations were made chiefly on new-born infants, in which he studied 

 the distribution of the labyrinthine fluid and found it present in the vestibule, the 

 cochlea, and in the semicircular canals. The same fluid was also referred to by 

 Cassebohm (1735) and Morgagni (1740). Up to that time no author had directed any 

 particular attention to the labyrinthine fluid, nor had anyone attempted to assign 

 any function to it other than that of moistening the auditory nerve. It was Cotugno 

 (1768) who first endeavored to show that the labyrinthine fluid had some connection 

 with the transmission of sound vibrations. He maintained that there was no air in 

 the spaces of the labyrinth, but that it was everywhere filled with the fluid, which 

 according to his description exudes from the ends of the capillary arteries that are 

 distributed throughout the membrane that lines the cavity of the labyrinth. He 

 described the fluid as being drained off by means of the two aqueducts. Because of 

 the completeness of his description and the interest which he attracted toward the 

 subject, the labyrinthine fluid was thereafter known for more than half of a century 

 as Cotugno's fluid. 



Any further advance regarding the nature of the labyrinthine fluid required a 

 more detailed knowledge of the soft parts of the labyrinth. Nerve-like cords and 

 semicircular tubes had been seen in the canals and membranous partitions and sacs 

 had been seen in the vestibule, but it remained for Scarpa (1789) to establish the 

 identity of the membranous labyrinth. He showed that in man and other mam- 

 mals the semicircular tubes and the vestibular sacs are of the same nature and form 

 one system, and that they are distinct from periosteum. He described how they 

 open freely into each other and are filled with a limpid fluid which distends them. 

 This fluid was thereafter referred to as the fluid of Scarpa. He recognized it in a 

 general way as distinct from the labyrinthine fluid, in which all parts of the mem- 

 branous labyrinth floated, but otherwise grants it no further attention. 



The relations and significance of the fluid of Cotugno and the fluid of Scarpa 

 were not completely recognized until the publication of the noteworthy monograph 

 of Breschet (1833) of which we have spoken. He introduced the terms perilymph 

 and endolymph, by which they have since been known. The existence of the coch- 

 lear duct was unknown to Breschet, but otherwise his description of the labyrinth 

 spaces and their contained fluids is the foundation on which the more recent descrip- 



