1918 Miles; on Behainor of Blennies 87 



The amount is no doubt affected by the action of HoS which was always 

 present. 



Reaction to hydrogen sulphide 



In the water samples taken from the habitat of blennies the HoS con- 

 lent varied from .296 cc. per liter at the surface to 1.39 cc. just above 

 the Ulva. In no case was it wanting where blennies were found, so far 

 as tested. In fact, the Laminarian belt would normally be expected to 

 produce HoS in some quantity. 



Despite the fact that sea fish are said to be sensitive to HoS, blennies 

 did not prove to be sensitive to any marked degree. In a gradient be- 

 tween 1.67 cc. and 3.34 cc. of HoS per liter, the individuals, while not at 

 all intoxicated, usually remained near the center. In no case was there 

 definite negative reaction. While this may not indicate an optimum HoS, 

 it should be noted that it is slightly in excess of the normal HoS content 

 of the environment of the blennies. Shelf ord and Powers (1915) noted 

 a sharp negative reaction in herring. 



Reaction to acidity and alkalinity 



The experiments with the reaction to alkalinity and acidity were car- 

 ried out with sea water. Great difference in density was avoided in this 

 way, as well as a difference in solutes which might affect the reaction. It 

 is true that the optimum on either side of neutrality could not be de- 

 termined. 



When NaoCOg and HCl were introduced at the 2 ends of the gradient 

 tank, a decided reaction was observed in the blennies. In one case the 

 turn M'as sharp at each trial. In all cases the final place of rest was the 

 extreme alkaline end. 



With an excess of HCl at one end and strong NaoCO., at the other, 

 the blennies still sought one end or the other, but never the center. A 

 positive reaction to alkalinity was not always indicated, but as the blennies 

 soon became stupid, extreme concentration of ions at both the inlets did 

 not force them away from the ends. When first put into the tank they 

 usually gave a positive reaction to the alkaline side of neutrality but soon 

 tame to rest at one of the ends. The ends were lighted with a little less 

 intensity this time, owing to the length of the candles. As it was found 

 that the acid floated while the alkali settled, a set of siphons was substi- 

 tuted for the outlets in order t© equalize the gradient. The reactions 

 were not changed by this. However, a eottid fish (sp..'') came to rest 

 on the acid side of neutrality. 



In another experiment no acid was introduced, and sea water con- 

 taining not more than a trace of COo was used against tlie strong alkali. 



