HuBER, Innovation of the Intracranial Vessels. 3 



correct understanding of the circulation of the brain, both in 

 its physiological and pathological aspect, that corroborative re- 

 sults obtained in the investigation of this fundamental anatomic 

 fact, can but extend and substantiate our knowledge of brain 

 physiology. 



In my own experiments I have used dogs, rabbits and cats. 

 For staining the nerves I have used the methylen blue method 

 of Ehrlich. After anaesthetizing the animal, the carotid was 

 exposed in the neck, on one side, and a canula inserted cere- 

 bralward. I then injected of a i % methylen blue solution, 

 made up in normal salt solution, a quantity sufficient to tinge 

 lightly blue the ear and eye of the side on which the injection 

 was made. It was found expedient to remove the thoracic and 

 abdominal viscera, and elevate the head of the injected animal 

 for a few moments after the injection, to allow as much of the 

 blood, as would do so, to drain from the head. Unless this is 

 done there is always oozing and bleeding during the removing 

 of the brain. Some thirty to forty-five minutes after the in- 

 jection, the brain and cervical cord were exposed, and to insure 

 against lacerating the pia-mater, the dura was, during this step, 

 injured as little as possible. After removing the dura, the cord 

 was cut about one inch below the junction of the vertebral ar- 

 teries and the brain removed. The cerebellum was then cut off 

 and an incision made into each cerebral hemisphere, and these 

 reflected outward. The brain was then placed on a glass plate, 

 base uppermost and exposed to the air for a period varying 

 from five to thirty minutes or until it was found that the nerve 

 fibers sought were stained. After some experimentation it was 

 found that preparations of the pia-mater could be most easily 

 made by dissecting off with curved scissors, pieces of the brain 

 cortex, and after placing these on a large slide, pial surface up- 

 permost, and covering them with a large cover glass, exerting 

 pressure sufficient to press the brain tissue out from under the 

 pia-mater. 



Even a delicate pia-mater — from the rabbit for instance — 

 may be treated in this way without laceration. This simple 

 method has the advantage of giving preparations which may at 



