382 BOTANICAL GAZETTE [may 



anesthetic. In every case tubes which contained only sea water 

 showed that the apparatus was not responsible for any of the 

 changes observed in the experiments in which tissue was used. 



The solutions used in any one experiment were always of the 

 same PH value, so that the results were comparable. Many of 

 the anesthetics, especially when in small concentrations, do not 

 appreciably affect the PH value of the sea water. A large number 

 of carboys of sea water, obtained from Woods Hole at the same 

 time, were filtered to remove organic matter in varying degrees, 

 the unfiltered material settUng to the bottom. When an anes- 

 thetic decreased the PH value only slightly, it was possible by a 

 suitable selection of the sea water from the carboys to obtain a 

 bottle of sea water of a PH value equal to that of the sea water 

 containing the anesthetic. 



Whenever large amounts of an anesthetic were used in the sea 

 water, it was considered advisable to add concentrated sea water 

 to bring the electrical conductivity of the solution up to that of sea 

 water. This was done with each of the following solutions: 

 sea water containing 16. i and 24.2 per cent alcohol respectively; 

 sea water containing 17.4 per cent acetone; and sea water con- 

 taining 3 . 2 per cent formaldehyde. Many of the experiments 

 were repeated at Woods Hole in the summer of 191 7. In these 

 experiments the solutions containing alcohol (all above i per cent) 

 were made of the same electrical conductivity as sea water. The 

 results were practically the same as when no concentrated sea water 

 was added. 



In the case of the higher concentration of formaldehyde, the 

 free acid was first neutralized with sodium carbonate. This is 

 allowable for the purposes of the present investigation, as its only 

 effect would be to make the amount of CO2 produced appear some- 

 what less than was actually the case. It should be understood that 

 the percentages of liquid anesthetics in the following descriptions 

 are percentages by volume. In an experiment in which there is 

 considerable dilution, as when absolute alcohol is added to sea 

 water to make a 10 per cent alcoholic solution, it might be con- 

 ceivable that the dilution might be the cause of the increased rate 

 of respiration. For that reason experiments were made with 



