112 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



statement, however, though generally true, requires qualification, 

 for under the influence of special stimuli the movements often become 

 directive. The larvae respond to varying directions and intensities 

 of light, and, in experimental tests, to the direction of electrical cur- 

 rents. They avoid, in many cases, light-colored objects if near, and 

 they are attracted by food to a rather slight degree. They will go 

 only very short distances, however, after particles of food or living 

 prey. During all the larval stages they exhibit practically no instinct 

 of fear and, while they avoid light surfaces, they do not try to escape 

 capture. The heliotropic and photopathic reactions and what may 

 be described as the general aimlessness of movement are things to be 

 reckoned with in developing a practical method of lobster culture. 



Food. — The natural food of the lobster must, of course, consist of 

 pelagic organisms. In an examination by Dr. L. W. Williams of 

 the stomach contents of larvae in all three stages taken from the rear- 

 ing bags at our station, * a large percentage were shown to have fed 

 upon copepods and diatoms. The young lobsters, however, are not 

 distinctly fastidious in this respect, and the nature of the stomach 

 contents of the fry in their natural habitat would doubtless be found 

 to vary according to the variety of available pelagic food. 



Moulting and the larval stages. — The instincts and behavior and the 

 general appearance of three successive larval stages are generally 

 similar in respect to the features just referred to. The stages are, 

 however, structurally well defined and readily recognized, there being 

 for each a number of clearly diagnostic peculiarities. (See figures in 

 text). Among the most obvious and easily recognizable are, for the 

 first stage, the small size of the larvae and the absence of swimmerets 

 on the under side of the abdomen; for the second stage, the somewhat 

 increased size, the presence of several pairs of swimmerets and the 

 absence of "tail fins" or the lateral appendages of the penultimate 

 segment; for the third stage, the presence of both swimmerets and 

 " tail fins. " All stages have the exopodite swimming appendages and 



* station of the Rhode Island Commission of Inland Fisheries at Wickford, R. I., on Nar- 

 ragansett Bay. 



