Mr. .1. S. 



the character of the increase which is confirmed by the results of other 

 experiments, the increase in the hypotonic solution is progressive, in the 

 other two there is an increase to, and a maintenance of, a steady 

 maximal weight. It seems evident that in all three cases there is an 

 imbibition of saline solution at first, apart from any question of the 

 transference of water through a membrane. 



The appearances of rigidity were noticeable in the nerve immersed 

 in the 0'6 per cent, solution, though the only index of their occurrence 

 found in the figures given is provided by the increase in length. The 

 occurrence of the appearances is, however, unmistakable in an actual 

 experiment ; the difference between a nerve which has been immersed 

 in 0-9 per cent, and one which has been in 0'6 per cent, is quite a 

 marked one. 



***** 



Markedly graduated as are the changes of weight, length, resis- 

 tance, and rigidity following the immersion of nerves in solutions 

 of graduated concentration, the changes in the E.M.F. available 

 between cross-section and longitudinal surface are no less so. In so far 

 is this true that it is possible, knowing the initial value of the E.M.F., 

 to predict the value which will be found after immersion of the nerve 

 for a given time in a solution of known concentration at a constant 

 temperature. 



The accompanying data are taken from the records of 8 entirely 

 separate experiments. In each, a sciatic nerve (cat), removed 

 immediately after the death of the animal, was. cut to a definite 

 length of 5 cm., and placed for 25 minutes in 500 c.c. of an XaCl 

 solution, at a temperature of 17 C. 



The E.M.F. found after immersion is given expressed in terms of 

 the initial E.M.F. used as unity, is called the KM.F. " recovered," 

 and as will be seen is sometimes greater than the initial value. 



Solution used. Proportion of E.M.F. recovered. 



(1) Tap water 1-5 



(2) 0-6 gramme XaCl percent 1*059 



(3) 0-75 0-921 



(4) 0-9 0-786 



(5) 1 -8 grammes 0'388 



(6) 3-0 0-237 



(7) 6-0 0-107 



(8) 9-0 0-062 



If in each case the value of the concentration of the NaCl solution 

 is multiplied by the E.M.F. recovered (expressed in terms of the 

 initial E.M.F.), we get a value which is almost constant for the whole 

 series. 



