318 



Transactions. 



glasses were not used, in order to allow of ready interchange of O2 and COj. 

 The results are shown in Table VIII (Exps. 126 to 134 inclusive). 



Table VIII. 

 Action of Tutin on Cilia. 



(Exp. 13-1.) The rate of progress of a small fi'agment of cork along the 

 surface of the gullet was noted before and after applying tutin (0"3 per cent. 

 in saline). Average rate before = 50'4" for 1 cm. travelled ; average rate 

 after = 34-8" for 1 cm. travelled. The method presented many difficulties, 

 as it is impossible to keep the fi'agment moving on the same line each time, 

 and the mucus secreted clogs its movements. 



From these results it is impossible to draw a definite conclusion, for 

 although in some specimens taken from sea-water animals the ciliary action 

 ceased on the application of tutin, in other specimens from the frog's gullet 

 tutin had little or no action. 



(c.) Action of Tutin on Striped Muscle and Nerve-terminations. 



This was tested by determining the strength of stimulus just sufficient 

 to cause contraction of a nerve-muscle preparation before and after the 

 application of tutin. The preparation (gastrocnemius - sciatic) was made 

 from the frog. An induction-coil with one Daniell cell and mercury-key 

 was used. The muscle in each case was placed first in normal saline 

 (0-75 per cent.) and the strength of the minimal stimulus determined. The 

 tutin solution was then substituted for the saline, and the excitability tested 

 from time to time. 



Four experiments were made (Exps. 135 to 138 inclusive). In three of 

 these the one muscle was placed in 0-025, 0-05, and in 0-5 per cent, tutin 

 solution, while the other muscle was placed in normal saline. In another 

 experiment the muscle of one preparation was placed in 0-5-per-cent. 

 solution tutin, and the nerve of the other in 0-5-per-cent. tutin. (Exp. 136). 



