OBSEKVATIONS ON SOME INFLUENCES OF LIGHT UPON 



THE LARVAL AND EARLY ADOLESCENT STAGES 



OF HOMARUS AMERICANUS. 



PLATES XXXVIII TO XL. 



PRELIMINARY REPORT. 



PHILIP B. HADLEY, 



BROWN UNIVERSITY, PROVIDENCE, R. 



The study of the influence of Hght stimuli upon marine animals 

 in general, and upon the group Crustacea in particular, has, during 

 the past decade, proved a fertile field for investigation. The wide 

 variation in the nature of the responses which may be called forth 

 by the influence of light of different intensities, of different colors, 

 and upon different backgrounds, has demonstrated the fact that the 

 habits of life of many forms may be regulated by, and even to a great 

 degree dependent upon, light changes; and, furthermore, that even 

 questions of relative nutrition, bodily strength, and rate of develop- 

 ment may be influenced, to no slight degree, by the light environment 

 which surrounds the individuals. 



With these facts in mind, and believing that further knowledge 

 of the influence of light upon the early stages of the lobster would 

 not only be of advantage to those engaged in the artificial propa- 

 gation of marine Crustacea, but would also form a further contribu- 

 tion to our data concerning the influence of light upon marine animals 



