May 17, 1907] 



SCIENCE 



785 



benders which attempt to eat the eggs. 

 The male himself eats some of the eggs, 

 but on account of the slowness of his diges- 

 tion is unable to eat more than a small 

 proportion, hence his presence is in the 

 main protective. In defending the eggs 

 the male is merely guarding his own food- 

 supply ; the origin of the brooding habit in 

 this case seems to be the feeding habit. 

 The eggs hatch about six weeks after ferti- 

 lization. The newly hatched larva is about 

 25 mm. long, and has a large yolk sac. 

 LarviB kept in the laboratory for two 

 months after hatching retain a remnant of 

 the yolk sac, and refuse food. Year-old 

 larvae are 6-7 cm. long, and retain the 

 external gills. Larvae two years old are 

 about 12 cm. long and the external gills 

 are greatly reduced. Sexual maturity is 

 attained with a length of about 34 cm. and 

 probably requires three or four years. 



Relations ietween Regeneration, the De- 

 gree of Injury, and Moulting in Young 

 Lobsters: V. E. Emmel, Brown Uni- 

 versity. 



The phenomena of regeneration and 

 moulting in the lobster present two distinct 

 processes of cellular activities. The one, 

 moulting, is going on more or less con- 

 tinuously throughout the period, or cycle, 

 between moults: the other, regeneration, 

 may be artificially induced at various 

 points within this cycle. The problem is: 

 what influence do these two processes exert 

 upon each other? 



A series of experiments were made on 

 fourth stage lobsters to determine— first, 

 the influence of regeneration upon the 

 duration of the moulting cycle, or period 

 between moults; second, the rate of regen- 

 eration at different stages of the moulting 

 cycle; and third, the effect of different 

 degrees of injury upon moulting and re- 

 generation. The results obtained seemed 

 clearly to demonstrate the following points : 



1. That the eifect of regeneration is to 

 retard the process of moulting; and that 

 this effect varies according to the time of 

 mutilation, so that the later the process 

 of regeneration is induced in the moulting 

 cycle, the greater is the duration of the 

 period between moults. 



2. That, on the other hand, the rate of 

 regeneration varies also according to the 

 time of mutilation, so that the later the 

 mutilation is made in the cycle, the more 

 rapid is the rate of the ensuing regenera- 

 tion. 



3. That the greater the degree of injury, 

 the slower the rate of regeneration, and 

 the greater the duration of the moulting 

 cycle. 



These experiments, therefore, indicate 

 that there is an interaction between the 

 two processes of regeneration and moult- 

 ing, of such a nature that the introduc- 

 tion of one will disturb the normal activity 

 of the other. Since, also, this interaction 

 varies at different times in the moulting 

 cycle, it emphasizes the importance of 

 taking this factor into account when draw- 

 ing conclusions from experiments made 

 upon Crustacea and other animals which 

 undergo ecdysis. 



C. JuDSON Hekkick, 



Secretary 



SCIENTIFIC BOOKS 

 L' Attention. By. W. B. Pillsbury. Paris: 



Doin, 1906. 8vo. Pp. 304. Bibliotheque 



Internationale de Psychologie Experi- 



mentale. 



A sufficient number of the fifty volumes 

 that are to form this series of handbooks of 

 experimental psychology have appeared to 

 justify the plan of the whole and to demon- 

 strate their serviceability. Professor Pills- 

 bury's volume on the attention is well con- 

 ceived and well executed; it is so particularly 

 from the point of view of the student, and 

 thus will be a welcome addition to the peda- 

 gogical literature when available in English. 



