548 F. W. rtAMBLE. 



what surpi'ising. 'J'he fish in both cases become green or 

 greenish, with brown bands. ^J^here is no well-marked 

 differential result, such as we shall find in dealing with 

 transmitted light. The yellow pigment is well developed and 

 well expanded; the red pigment, however, showed more 

 expansion in green backgrounds than in red. This coloration 

 is one intermediate between a white and a black background 

 result. In the case of red weed the effective rays are the red 

 or the red-orange, and so far from these encouraging the 

 develop ent and expansion of the red pigment they seem to 

 have the contrary effect, for from August 14th to 20th the 

 records all run green, and thongh there is a subsequent period 

 of darkening the red colour is not noticeable. The inference, 

 therefore, is that in the case of red weed the red end of the 

 spectrum is concerned in the formation and expansion of 

 yellow pigment. In the case of green weed the results are so 

 similar as to leave the specific action of the green rays 

 uncertain. The red and orange rays, both of green and of red 

 weed, appear to act alike, while the bright green rays of Ul va 

 or the dull green of Nitophyllum does not exert any very 

 definite action. 



(4) Influence of Light transmitted through Algaj. 

 (Table II, p. 576, and PI. 23, figs. 2 and 3.) 



When, however, the experiment of transmitting light 

 through a thin layer of algal tissue is made, the results are 

 not only more definite but also help to interpret the former 

 experiment. 



Table II gives the records obtained by exposing young 

 wrasses of the same species as those employed for the preced- 

 ing work, to light transmitted through two fronds of green, 

 brown, and red weed respectively. 



For this purpose two rectangular museum jars were 

 employed. The inner one contained the fish, and was 

 separated on three sides by a chink about 1 cm. wide from 

 the outer, the space being filled with water and fronds of the 



