Growth of Brain and Viscera in Dogfish 323 



by calculating a series of average weights of each organ in successive 

 groups of individuals, and the line formed by connecting these averages 

 was then smoothed to a curve so as to reduce to a minimum the plus 

 and minus deviations of the averages. The groups from which the 

 averages were derived varied in extent from 100 to 1,000 grams in dif- 

 ferent regions of the entire group, according to the rate at which the 

 character of the curve was changing. 



The fish themselves were taken, with very few exceptions, from a single 

 trap in Buzzards Bay, and in nearly every case they were examined 

 within twenty-four hours after their removal from the trap : during this 

 interval they were kept in tanks abundantly supplied with running 

 water. A few specimens had been kept for a few days before weighing 

 in a large floating car in very favorable conditions. In determining 

 total weights the fish were dried off with a towel and the weight of stom- 

 ach contents subtracted: the ovaries and oviducts, even when containing 

 embryos, were included. 



The total number of fish examined was 315 (176 females, 139 males). 

 Of these, the brains of 65 and the gonads of 15 were not weighed. These 

 fish did not form a "random sample," but were of sizes selected so as to 

 give as complete and uniform a series as possible. Practically all of 

 the larger individuals taken were examined, but only a small proportion 

 of the smaller and medium sizes. Consequently many of the usual 

 statistical constants ernployed would be of no comparative value as 

 descriptive of this group and they have not been determined. As may 

 be seen from the plates the fish ranged in size from those just born, 

 having an average weight of 76.2 grams and average length of 32.8 cm., 

 up to a female weighing 8434 grams, length 135.1 cm. The specimens 

 examined at birth, of which there were thirteen, were born in the labo- 

 ratory from a single female (I believe this is the maximum number of 

 young recorded for this fish) and it should be borne in mind that in 

 speaking subsequently of the condition of certain organs "at birth," 

 these specimens alone are referred to. Since these were all obtained 

 from a single female and that the largest taken during two seasons' 

 collecting, the weights found may not represent accurately the precise 

 average condition at birth. 



The series of fish examined shows, then, an increase in weight of over 

 110 times and in length of over four times. From a small number of 

 fish collected wholly at random the average weights and lengths were 

 found to be about, males, 1050 grams, 73 cm. ; females, 1800 grams, 87 



