54 ON THE PRESERVATION OF ENCEPHALA 



much greater ease and rapidity than is the case in brains not thus 

 treated. Especially is this the case in the brains of foetuses, in 

 which, whilst the substance of the convolutions is softer, the 

 amount of their vascular supply is relatively much greater than 

 in adults. 



I have little to add to these recommendations except in the 

 way of confirmation based upon the results attained by applying 

 this method to specimens to be preserved permanently in catalogued 

 series. And I may say that a permanent specimen of a brain 

 of any vertebrate animal which has been treated with zinc chloride, 

 either* injected by the umbilical vessels, as is to be done in the 

 case of foetuses, or otherwise brought into relation with it, 

 contrasts very usually with a brain which has been treated with 

 alcohol alone, in having a much smoother and less grumous sur- 

 face than brains treated in this latter fashion, however pains- 

 takingly their membranes may have been picked away from them. 

 The difference may be illustrated by saying, that the surfaces of 

 two sets of brains, thus severally treated, differ very much in the 

 same way that the surfaces of the bones of wild and domesticated 

 representatives of the same species differ. 



But, secondly, I would say that the condition of freshness is by 

 no means absolutely necessary for the purposes of making anato- 

 mical preparations of brains, as M. Stahl appears to have found it 

 to be for the purpose of modelling. Having to deal with the 

 brain of a large toper shark (Galeus canis), some way removed from 

 that condition of freshness which would have rendered it safe to 

 attempt to remove it from the skull, I treated it for some days 

 in situ, firstly with zinc chloride, and subsequently with spirit. 

 After this, it bore removal from the skull, as well as the brains of 

 its congeners, which came into our hands in more favourable con- 

 ditions, and in this matter of smoothness and clearness, and what 

 the Germans call the 'Glanz' of its surface, it compares to con- 

 siderable advantage with them (see Prep. 896, b. e. Anatomical 

 Department, Oxford Univerity Museum). For the successful 

 application, however, of Broca's method of hardening and shrinking 

 a brain by nitric acid, for which see ' Mem. Soc. Anthrop., Paris/ 

 ii. 1865, p. 84, into a mass which, when dried and varnished, bears 

 handling for an indefinite period ; I take this opportunity of 

 saying that I incline to think the condition of freshness is usually 



