THE NEURO-MUSCULAR SPINDLE 121 



Ranvier lemon-juice method. This method is essentially that 

 used by Bardeen ('02) in his work on the cerebro-spinal nerves. 

 The fresh tissue is placed for five to ten minutes in freshly ex- 

 pressed and filtered lemon-juice, until translucent. It is taken 

 out and washed rapidly in distilled water; then transferred to a 

 1 per cent gold chloride solution for fifteen to thirty minutes, de- 

 pending upon the size of the tissue. After this it is again washed 

 in water and placed in 33^ per cent formic acid (Kahlbaum) in 

 the dark for twenty-four hours. The tissue is now placed di- 

 rectly in glycerine and examined for nerve endings. 



While this method is fairly satisfactory with adult tissue, it is 

 much less so with embryonic muscle. I soon abandoned it be- 

 cause I found it practically impossible so to regulate the various 

 factors in fixation as to secure any constant results. At best the 

 method seemed to be very capricious, with great odds on the side 

 of failure. Next, I decided to adapt for my use in embryo pigs, 

 if that were possible, the method of intravitam staining with 

 methylene blue, which has impressed me as being the method of 

 choice at the present time in work upon nerve endings. Most of 

 the best work upon adult neuro muscular spindles has been done 

 with this method. Besides, Wilson in his article in The Ana- 

 tomical Record ('10) has described so completely even the finest 

 details of the method, together with the possible sources of error, 

 that there is little excuse for not securing constant results. In- 

 deed, it was the simplest thing to make a few alterations and so 

 adapt it to use with the embryo pigs. I realize that there are 

 dangers in confining one's efforts to a single method in any 

 study upon the structure of the nervous system. The use of 

 several methods would be valuable as a check upon each other. 

 I feel, however, that with access to sufficient material one can, 

 especially with the methylene blue method, keep away from 

 errors of this sort, because one can control the accuracy of his 

 findings by the constancy with which they can be demonstrated. 

 The constant findings of a single method are perfectly valid 

 whether they be verified by other methods or not. The fact 

 that certain details seen with one method do not show up with 

 another does not prove their non-existence but rather the specific- 



