io8 Neurological Technique 



It is best not to attempt dissection until the organ is 

 thoroughly hardened. Human brains should be given 8-10 

 days in the fluid. Smaller brains will harden sufficiently in 6-8 

 days ; 3-5 days will be amply sufficient for the spinal cord. 



The specimens may remain in the formalin solution for 

 years without injury in any way. Only the vessel should be 

 kept tightly covered, lest the solution become too much diluted 

 by the evaporation of the formaldehyde. 



3. Dissection. — Before beginning dissection place the speci- 

 men in water long enough to remove the formalin sufficiently 

 that it may not be objectionable to the hands, eyes, and nose. 

 During the dissection keep the specimen moist with water. 



When it becomes necessary to rest the dissection for 12 

 hours or more, simply return the specimen to the vessel of 

 formalin and, when the dissection is to be resumed, transfer it 

 to water again, and so on, till the dissection is complete. For 

 an interval of 12 hours or less the specimen may remain in the 

 water without injury. A longer time may possibly cause 

 maceration. . 



Specimens prepared in the above way will be found to 

 possess the normal shape and very nearly the normal size ; they 

 will be tough and elastic, and capable of much tearing and 

 teasing; their color will be little altered and the blood 

 pigments so little extracted that the blood vessels may be 

 followed in considerable detail. 



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