434 



EDWARD HORNE CRAIGIE 



Injection with diluted India ink was tried, but gave less satis- 

 factory results. As soon as injection was completed, the neck 

 was ligatured and the whole head was cut off and immersed in 

 chilled fixing fluid until the gelatin had time to set. The top 

 of the skull was then opened and, if the gelatin was not yet firm, 

 the head * was returned to the fluid. Finally the brain was re- 

 moved and left in the fluid for three and a half to five hours more. 

 The earlier specimens were left longer, but the injection mass 

 was found to be decolorized by the picric acid, so the time had 

 to be cut down. For this reason several brains were fixed in 

 10 per cent formalin for five days, but this method was aban- 

 doned in favor of the brief treatment with Bouin, the findings 

 of previous workers, as well as the observations of the writer, 

 indicating that less distortion would thus be produced. 



Bouin's fluid was used as a fixing agent for two reasons. In 

 the first place, the strong formalin would give a good hardening 

 of the gelatin; in the second place, Sugita ('17) has shown that 

 this solution causes less change in volume than do others com- 

 monly employed. 



After fixation the material was rinsed, dehydrated in the 

 ordinary way with graded alcohols, and imbedded in paraffin. 



To determine how much change this treatment produced in 

 the brain, two specimens were carefully weighed and measured 

 as soon as removed from the skull, and again after fixation and 

 after dehydration. There was found to be practically no change 

 in shape or size during fixation, though there was an increase 

 in weight, as would be expected. After dehydration the changes 

 were as follows : 



Loss in weight 



Loss in volume 



Loss in area of sections 



