LECTURE III. 79 



those used by Tiedemann. Morton used peppercorns or shot, 

 andj instead of weighing, he measured them, by which he 

 obtained the advantage that measure corresponded to measure 

 and not to weight. Huschke used water, measuring the 

 quantity requisite for fiUing the skull ; here, of course, the 

 temperature of the water must be attended to. The results 

 thus obtained I shall presently indicate. 



There can be no doubt that skull and brain exercise a reci- 

 procal influence as regards development ; that they grow with 

 each other, but that the details of the superficial formation 

 depend on the mechanical action of the brain. The inner 

 surface of the skull represents, therefore, the impress of the 

 surface of the brain, but, be it understood, of the brain invested 

 with its integuments. Now, the hard, external membrane of 

 the brain, the so-called dura mater of anatomists, forms a cover- 

 ing, which passes above the inequalities and the convolutions 

 without entering into the depressions which separate them. A 

 cast, filling the cranial cavity, and preserving its shape after 

 removal, will therefore represent only the coarser features of 

 the brain, but not the minute details. There has been a great 

 deal of dispute as to the substance best fitted for this purpose. 

 To supply, says Huschke, the want of brains of various na- 

 tions, I have made wax models from the crania of a Carib, 

 Cossack, etc., which afford some idea of the convolutions. 

 Wagner used gypsum, Lucae glue ; the latter is of opinion 

 that there is no substance more suitable for rendering the 

 form, size, and circumference of the brain.* Gypsum has, 

 however, the advantage of retaining the form of the effusion, 

 whilst glue only retains it for a few days. Both sub- 

 stances have the disadvantage of uniting with water in dif- 

 ferent quantities, and consequently vary in weight. Hence, 



* Compare Flower on " The Brain of Siamang," Nat. Hist. Rev., 1863, for 

 details of the method employed by him in the preparation of the series of 

 casts in the Eoyal College of Surgeons by the use of a composition of glue 

 and treacle. — Editor. 



In the second part of Zur Morphologie der Rassenschadel, Frankfurt, 1804, 

 Lucae recommends the use of seed, as he finds that the specific gravity of 

 the glue-casts varies so greatly, even when taken from the same liquid mass, 

 that it is quite impossible to determine the volume of the brain by means of 

 such casts with anything like accuracy. — Editoe. 



