82 Pub. Puget Sound Biol. Sta. Vol. 2, No. 37 



was the only factor changed, we must consider the relative amounts of 

 carbon dioxide given off as a factor in the negative reaction as well as 

 direct reaction to light. The lowest tides on Brown Island occurred, for 

 the most part, during the night or early in the morning, which corresponds 

 to a period of inactivity in photosynthetic work by the sea lettuce and a 

 corresponding decrease in the liberation of oxygen. This was the most 

 common time of investigation, and blennies were found high on shore. 



Response to current (rheotaxis) 



Attempts to determine the reaction to current were made in a rheotaxis 

 tank, but no quantitative work was attempted. Blennies do not seem to be 

 as sensitive to currents as many other fishes. Of the individuals used, very 

 few turned to breast the current. The reaction was usually in the direc- 

 tion headed. If this opposed the current the effort was increased. The 

 result of a current stimulus was the seeking of a sheltered object or corner 

 without reference to direction. However, resistance to being carried out 

 of their position by the current was always offered. In a tub, circular motion 

 and heavy washing, resembling wave motion, were not noticeably resisted. 



Reactions to light and color 



The fact that blennies live under stones while out of water suggested 

 a study of their reactions to light. These were obtained by use of the 

 pans described. Since the fish reacted positively to the ends and corners, 

 the glasses in the color experiments were interchanged so that each occu- 

 } ied the three sections at different times during the experiment. The ends 

 of the pans were occasionally reversed to serve as a control on other con- 

 ditions. Readings of the number of blennies in each third of the pan 

 were taken every 5 minutes, usually for an hour, and recorded under the 

 proper head. At the end of each experiment all of the readings for 1 

 compartment (or color) during the series of 5-minute periods were added. 

 The ratio of any one such sum to the grand sum for all the compartments 

 is taken to indicate the reaction to a definite light-condition or color and 

 is expressed as percentage. For the sake of comparison, percentages 

 rather than numbers of individuals are given in table 1. 



10 blennies of various species from various habitats were placed into 

 the white compartment of the color box. The individuals included were 

 (a) dark olive-blue; (6) gray; (c) mottled, with light fins; {d) light 

 grass-green; while one had bright red-orange fins and markings. No per- 

 manent selective reaction was shown which could be due to individual 

 color, and all location seemed to be a matter of chance. 



