410 



BECORD OF CURRENT RESEARCHES RELATING TO 



colour was carefully compared with that of the spectrum, and means 

 were taken to prevent any affection of the results by differences 

 in the water, temperature, and so on. The glasses were (1) red, 

 which absorbed all light from violet to the line C of the spectrum ; or 

 (2) blue, which cut off the red from B to C and the greenish-yellow 

 from C to D ; or (3) yellow, which only allowed the red, orange, 

 yellow, and green rays to pass ; or (4) green, which absorbed the red 

 to the line C and cut off the violet. At first the developmental 

 processes did not differ among the different ova, or from those which 

 were exposed to ordinary daylight. When rotation commenced it 

 was found that the eggs exposed to red light rotated most rapidly ; as 

 this is due to the action of the cilia, and as the cleavage processes were 

 still similar in all, we may suppose that red light has some exciting 

 influence on the cilia. When the tail and its musculature were 

 developed the most evident movements of the former occurred in those 

 larvfe which were exposed to red light ; those under the blue glass 

 were nearly or quite inactive. Similar results were obtained when 

 the circulation was completely in function ; the larvae under the red 

 glasses were still the most active of all. Great torpor was exhibited 

 by those under the blue glass, while the rest, exposed to yellow or 

 green light, differed not at all from those developed under uncoloured 

 glasses. The most greedy were those under the blue glass. When 

 brought from their artificial influence its effects gradually passed off. 

 When changed from one colour to another the activity displayed 

 became gradually more or less. 



Leaving other investigations we come to the resolution of the 

 question which Moleschott and Fubini have set themselves: does the 

 light act directly on the body, or by means of the eyes, in affecting 

 the excretion of carbonic acid ? The results are given in the follow- 

 ing table : — 



