236 CHESTEK H. HEUSER 



The form of the ventricles in the adult pig has apparently'' 

 never been studied bj^ means of casts or models. Figures 25 

 and 26, representing the cerebral ventricles in an embryo of 

 260 mm., are however very similar to those which would be 

 obtained from an adult and they ma}^ be compared with Dexler's 

 figure of the cavity of the brain in the horse, and with any one 

 of several figures of the ventricles in the human brain. The 

 first of these were published by Welcker (78) who filled the 

 ventricles with wax, injecting through the infundibulum, and 

 published figures and a brief description of the model thus ob- 

 tained. Testut ('97) figured and described a plaster cast of the 

 ventricles. Barratt ('02) constructed a wooden model from 

 measurements obtained from thick sections (12.5 mm.). From 

 the method employed accuracy of detail could scarcely be ex- 

 pected. By far the most delicate and satisfactory' figures are 

 those of Retzius ('00) who made casts by the use of Wood's 

 metal. Harvey ('10) has recently used Wood's metal for the 

 same purpose with similar results. 



In the human brain immediately above the pineal body there 

 is a backward extension of the cavity of the third ventricle which 

 forms the supra-pineal recess. This term was introduced by 

 Reichert ('61, Bd. 2, S. 69) who described the structure and 

 showed its relations in median sections of the brain. In his fig- 

 ures the recess measures nearly 5 mm. in length. In Welcker's 

 plaster cast it appears to be somewhat larger and in the cast 

 by Retzius it measures 10 mm. But Testut and Harvey show 

 onl}^ very slight protrusions. The recess may be variable in the 

 human brain. In Dexler's model of the ventricles in the horse 

 it is a very conspicuous object, nearly 25 mm. in length. In 

 the adult pig it measures 5.5 mm. In proportion to the size 

 of the third ventricle it is very much longer than in man but 

 much shorter than in the horse. The significance of this recess 

 has not been determined. 



A very conspicuous feature of the casts of the third ventricle 

 is the aperture made by the massa intermedia. In the several 

 models of the human brain this aperture varies considerably in 

 size, but in no case is it as large as in the pig or the horse. In 



