NO. 14.M. BRAINS AND BRAIN PRESERVATIVES— HRDLICK A. 303 



nature; fortunately they are not, at least in normal animal brains, 

 very serious. 



The effect of dail}' weighing the brain was, almost generally, greater 

 than the average loss of weight. 



The changing of solution after one week and one month had in a few 

 instances no appreciable effect, but mostly there was a consequent tem- 

 porary (one to two days) rise in weight which acted as a retarder of 

 the continuing loss. 



As to the practical results of these experiments on the value of various 

 brain preservatives for macroscopical purposes, it is plain that neither 

 an}' of the simple formalin solutions nor any of those to which common 

 salt or alum had been added, is satisfactory. The changes in these 

 liquids are considerable and their continuation prolonged, while there 

 are no compensatory advantages. No good purpose would be served 

 by using any of these mixtures, with one possible exception, in the 

 future; the exception concerns the addition of alum to the solution 

 used for brains of foetuses or the very young, for the purposes of 

 increasing the hardening. 



On the other hand, the results obtained with the alcohol and formalin 

 mixtures are most encouraging. These liquids have produced but 

 moderate initial changes (much of which can be done awa}^ with by 

 proper modifications of the solutions), followed by the all important 

 feature of subsequent stability. The permanence of this stability has 

 not received as yet a sufficient test of time, but Donaldson's prolonged 

 observations with other alcohol mixtures render it highly probable. 

 The brain is not affected perceptibly by the necessary changes of solu- 

 tion. At all events, it is with this class of preservatives that further 

 experiments are most justifiable. 



The addition of the salts in Stroud's liquid gives no superiority over 

 the simple alcohol-formalin solutions. The greater specific gravity of 

 the mixture would commend it on account of the slightly greater pre- 

 vention of deformation in the specimens, but the somewhat greater 

 initial loss in weight and the subsequent continuous gain are disad- 

 vantageous. If equally good results, so far as weight and size of the 

 specimens are concerned, can be obtained with simple mixtures, these 

 should be preferred. Conservation of the form of a specimen in any 

 preservative is largel}^ a matter of proper care. 



As a result of the data obtained by the experiments reported upon 

 in this paper, the tentative regulations below outlined concerning brain 

 preservation have been made in the laborator}- of ph3^sical anthropol- 

 ogy of the U. S. National Museum. They can, it is hoped, be pur- 

 sued with daily and longer periodical weighings of the specimens, and 

 with whatever modifications may become indicated in the liquids, until 

 a substantiated and as simple as possible method of brain preservation 

 has been determined. It would be ver}' desirable if a concurrent 



