NATURAIv HISTORY OP AMERICAN LOBSTER. 327 



In order to ascertain as exactly as possible the age of our young lobsters, we determined to collect 

 them for the space of twelve hotu-s, a circumstance which led us first to find that hatching never takes 

 place by day. At from six to seven o 'clock in the evening not a larva was visible in the water of the float. 

 Two hours later we could see several hundred of them swimming about. If we removed all of the 

 latter with care, no new arrivals appeared before the evening of the following day. To what was the 

 rapid emission of larv» in so short a time due? The continual observation of our float during the 

 first hours of night soon showed us the key to the enigma. 



Toward seven to eight o'clock in the evening the female- commenced to stir herself in her prison 

 by presenting an attitude altogether unusual and characteristic. Her feet are stretched out almost 

 rigid, her tail extended to the full in a horizontal direction, forming, with the rest of her body, 

 a nearly straight line. She walks, as we might say, upon her toes, so careful is she to hold her entire 

 body as far away as possible from the bottom of the aquarium. This feat lasts for a certain time; then 

 quickly lowering her head and the fore part of her bodytmtil she rests upon the ground between her out- 

 spread claws, with tail on the other hand raised at an angle of 45 degrees and kept stretched, we see 

 her violently shake her swimmerets with such rapidity that the eye cannot follow the movement, 

 and a veritable cloud of larvae are sent far to the rear and dispersed in all directions." This phenomenon 

 lasts from 15 to 20 seconds, and the female thereafter returns to her habitual attitude, to depart there- 

 from no more until the following evening. We have repeatedly verified the fact by observing always 

 that the larval emission is produced in certain cases by two series of distinct movements, lasting some 

 minutes, the second producing much fewer larvae than the first. 



The hatching does not therefore proceed independently of the mother and does not take place at 

 all times of the day and night, but is confined to the hours of eight to nine o'clock in the evening. 



The first molt which follows hatching is effected in the hours which precede the emission, and it 

 is without doubt the movement of the larvse under the abdomen of their mother which causes in her 

 these signs of agitation and unrest already described. If, in short, one tries to draw the female out 

 of the water when ip this condition, we can see in her movements of defense the downfall of a great 

 number of larvffi previously hatched but doubtless united to their mother by the molted membrane which 

 her violent movements sufficed to break or to detach. Unfortunately we have been unable to assure 

 ourselves whether, as Laguesse has observed in the crayfish, the young are found attached by the telson 

 to the debris of the shell or of the molt (compare p. 167). 



It should be noted that on occasion larvae appear to be normally hatched in the 

 daytime, and that a few may even resist the movements of their mother to disperse 

 them, and remain for some little time attached to her body, though capable of swim- 

 ming. In regard to the hatching of the European lobster when confined in ponds 

 at the marine fish hatchery and biological station at Portobello, New Zealand (see p. 298), 

 Mr. Anderton has written to me as follows: The hatching "almost always takes place 

 at night. I say almost advisedly, since this last season a batch has frequently been 

 hatched during the afternoon by a violent aeration of the tank water. I think about 

 1,700 has been the largest number hatched from a single individual during one night." 



THB HATCHING PROCESS. 



As already observed, what we shall consider the first molt of the larva is passed at 

 the time of hatching, and in this act the larval cuticle and shell membranes are shed 

 together. The stalked secondary egg membrane, representing the glue or fixative by 



" with this specific and graphic account compare the brief statement of Coste, made nearly a half century before, that 

 "The brood females straighten their tails, which up to now have been carried bent against the plastron, gently oscillating those 

 appendages to which the bunched embryos are attached, as if to scatter the larvae, and to aid them in breaking the shell, and 

 hus free themselves in the course of a few days of their entire cargo." {ss< P- 205). 



