NATURAL HISTORY OF AMERICAN LOBSTER. 357 



REACTION TO OTHER STIMULI. 



The results of galvanic stimulation are particularly interesting, since they appar- 

 ently represent a fundamental response of living matter, this particular form of energy 

 being unknown under natural conditions. It was noticed by Hadley (129) that the 

 young lobsters reacted very definitely to the galvanic current by gathering at the anode. 

 Under the influence of the ascending current a progressive orientation to the anode 

 took place, providing the long axis of the body came into certain relations to the current. 



Hadley has also described an interesting rheotactic response in lobsters of the fourth 

 stage, in accordance with which they head to the strong circular current which is main- 

 tained in the rearing bags or boxes at the fisheries station at Wickford, R. I. Even within a 

 minute after molting to this stage the lobster would face about and head into the current, 

 swimming so actively as to make some progress if the force was not too strong. "This 

 characteristic manner of swimming, says Hadley," "was evinced in an ever-increasing 

 number of lobsters, until the whole body of them had passed into the fourth stage, and 

 then it was a most interesting sight to observe the young animals, with hardly an excep- 

 tion, heading into the current and as a great phalanx following their circular course — 

 but, because of the force of the current, backward." 



This rheotactic response is if anything stronger by night than by day. It may be 

 modified or lost by passing from shadow to full light in the daytime or from darkness to 

 strong light at night, the phototactic response overcoming the influence to swim against 

 the current. Rheotaxis is due in some measure to a stimulus which, as Hadley believes, 

 reaches the nerve centers through the eye. It is gradually lost in the fifth stage. 



MOVEMENTS OF THE YOUNG LOBSTER IN A STATE OF NATURE. 



We will now review the probable behavior of the young swimming lobsters in their 

 natural state in the sea, in order to ascertain to what extent experimental work in the 

 laboratory has enabled us to understand their complex movements. It must be admit- 

 ted that comparatively little is definitely known through direct observation upon the 

 subject. 



Under natural conditions the young of the lobster, as in many of the higher Crus- 

 tacea, are presumably hatched at twilight or at night at the sea bottom, their dispersal 

 taking place in the way already described (p. 327). Possibly under some conditions they 

 swim to the surface during the night of their birth, while as a rule they may not make 

 the ascent until stimulated by the light of returning dawn, but remain at the higher 

 levels for a few days only. This is confirmed by captures with the tow net by both day 

 and night (p. 331) and by the experiments of both Bohn and Hadley, already recorded. 



Then follows a period of greater fluctuation, embracing the latter part of the first 

 and the two remaining larval stages, during which their movements are variable. 

 Though still coming to the surface and within reach of the net, their capture in this 

 way, at the present time at least, seldom occurs under any conditions. Presumably in 

 shallow waters they even settle at times upon the actual bottom, but their usual beat 

 or range of movement, especially in deeper waters, is not known. Experiment has shown 



