120 TEIJI HOSHINO 



Winkler, Dogiel, Munzer and Wiener, Boyce and Warrington, 

 Murphy, Ziehen, Williams and Brouwer) . It is not easy, there- 

 fore, for any one to study accurately any changes that have 

 occurred in the nervous system of the pigeon. For this reason 

 each section of the affected birds was treated quite the same way 

 as a corresponding control section. This not only gives us a 

 comparison with the normal structure, but also serves to show 

 us any artefacts that may be present. 



The birds were narcotized with ether, while I opened the cranial 

 cavity and spinal canal to take out the whole brain and spinal 

 cord. During the time of the removal the brain and cord were 

 both rinsed in physiological salt solution, and before fixation, 

 measured and weighed. The brain stem, cerebellum, and the 

 spinal cord of both the normal and affected birds were used for 

 microscopic examination. The brain was cut through proxi- 

 mally at the level of the posterior third of the optic lobes and dis- 

 tally at a point separating the medulla oblongata from the spinal 

 cord. Half of the cerebellum was left attached to the medulla 

 and the whole fixed in 10 per cent neutral formalin solution, while 

 one portion of the half of the cerebellum removed was fixed in 

 Zenker's formalin solution and the other in alcohol. The fol- 

 lowing is the formula for Zenker's formalin solution used: 



Bichromate of potassium 2.5 grams 



Bichromate of mercury 5 grams 



Sodium sulphate 1 gram 



Formalin 10 cc. 



Distilled water 100 cc. 



From the spinal cord two parts were taken, one from the cervi- 

 cal region and the other from the lumbar region. Each piece was 

 cut into three divisions, one put in Zenker's formalin, one in 10 

 per cent neutral formalin, and the third in alcohol. Each speci- 

 men had a control piece from the normal bird and both were 

 treated the same way in the same bottle. After fixation, regular 

 dehydration followed with both pathological and control speci- 

 mens. Both pieces were imbedded in the same block of paraffin 

 and cut wit h the microtome at the same time. With each stroke 

 of the blade, then, two seel ions would be made, one pathological 



