236 BULLETIN OF THE BUREAU OF FISHERIES. 



thus becomes a means of drawing out or evaginating every microscopical haii of the 

 newly-formed armor. 



This adjustment is even more complicated in the young lobster about to hatch. 

 Its " swaddling clothes" are so piimed together that all come off as one piece; the animal 

 hatches and molts at the same time. The outer egg membrane splits lengthwise like the 

 skin of a pea; it is glued in certain places to the iimer membrane or true egg shell; this 

 adheres to the outer deciduous cuticle, which in turn sticks at innumerable points to the 

 hairs; by the time the animal has kicked off its covers it is thus ready to swim, for 

 every hair is drawn out to its full length. 



In hatching the eggs of lobsters by artificial means in jars or boxes, this delicate 

 adjustment often fails at one point, and the little animal is doomed. The egg membranes 

 fail to stick, and thus to pull out the swimming hairs, so that the young lobster is hatched 

 in a helpless condition. It struggles in vain, a prisoner inside of its own skin, which it 

 is unable to shed. 



Blood pressure is another factor which enters into this important process of evagi- 

 nating the setae, and in all adult lobsters withdrawal of the blood from the great claws is 

 an essential condition of the molt. As a consequence, when the animal escapes from the 

 old shell, the hair clusters on the deformed plastic flesh of the great claws are scarcely 

 visible, while they are prominent in other parts. With returning blood pressure the 

 hairs of the toothed claw are fully evaginated. It seems evident that when once the 

 shell has become hard no further evagination of the hairs is possible. 



From the method of formation of new hairs it follows that at each molt, as Prentiss 

 has shown, the nerve fibers lose their connection with the old hairs and enter into 

 relations with the new ones. 



TOUCH. TASTE, AND SMELL. 



As long ago as 1868 Lemoine {179) suggested that the senses of taste and smell in 

 higher Crustacea might be blended with that of touch, and while msiny able workers 

 have since attacked this problem and produced far better results, we are still unable 

 ^ojpeaJi^with^rnuchjxsctness upon the subject. As I have shown by earlier experiments, 

 nearly every part of the lobster's body is subject to tactile or chemical stimulation, and 

 must therefore be supplied with sense organs of some sort. (See 149, p. 129.) We found 

 that the parts most richly supplied with setae, with the exception to be noted below, were 

 most sensitive, and it seemed evident that all the soft setae, whether fringing and pro- 

 tective or not, were sensory. It was further observed that the greater sensitiveness 

 was lodged in the antennules, and especially in their outer whips, which bear the peculiar 

 club-shaped setae, the antennae, the tips of the slender legs, and in younger animals, at 

 least, in the fingers of the big claws. Stimulation with various gases and liquids, injected 

 with a pipette upon a given part, gave more or less prompt reflexes either in the limb 

 itself or in the appendages nearest the part affected. If any stimulus, whether electrical, 

 tactUe, or chemical, -be applied to the right* second, maxilla or right first maxillijed, 

 vigorous chewing movements are immediately started in the affected appendage of that 

 side, and may spread to the side opposite. 



