308 S. Simpson, 



Vassale [3] adds to Marclii's solution a small quantity of nitric acid. 

 Both these modifications were tried, but in my hands neither of them 

 has been very successful. My best results have been obtained either 

 with old fluid (i. e. fluid which has been used over and over again), 

 to which a little fresh osmic acid was added from time to time, or 

 by using Marchi's solution prepared from Miiller's fluid in which some 

 brain tissue had been immersed for several months previously, a me- 

 thod adopted by Hamilton [31] in staining sections. Either of these, 

 I am convinced, will reveal fine degeneration where the freshly pre- 

 pared Marchi fluid will fail to do so. 



Methods of testing effects of lesion on motion and sensation. 



In testing the motor and sensory symptoms which followed from 

 the lesions, the method adopted was as follows: — If the animal was 

 tame and quiet, it was taken out of the cage and allowed to move 

 about the room, when its general attitude and mode of walking were 

 observed. In the case of monkeys the manner in which they used 

 their limbs in climbing was noted. To test voluntary power in the 

 arms, the animal (monkey) was offered a small piece of banana or 

 apple, or, a few currants were placed upon the floor within its reach, 

 and its ability or inability to take or pick up these was noted. In 

 the case of the hind limbs, the animal was lifted up, and gently 

 swung towards the wire-netting of the cage, oi- dropped towards (but 

 not on to) the floor. If the animal possesses the poAver of voluntarily 

 moving its limbs, both ai'e extended towards the cage or floor, but if 

 voluntary power is absent in one or other of the limbs there is no 

 such movement of that limb. With an animal suspended in this way 

 the paralysed limb hangs pendulous while the non-paralysed limbs 

 are usually drawn up somewhat. Voluntary power is much more 

 easily tested in the monkey than in the cat, but when the latter is 

 suddenly dropped towards tlie floor (on all fours) there may be no 

 movement of the non-paralysed limb or limbs as a whole, 1)nt in the 

 normal animal the toes are always extended and spread out as tlie 

 foot approaches the floor, i. e. an attempt is made to catch tlie floor. 

 No such movement of the toes, however, is observed in a paralysed 



