122 BENNET M. ALLEN. 



bowl in which they were kept no doubt retarded their growth. 

 They showed the following characters as to color and size : 



No. Specimens. 

 Dark but with a more silvery cast than usual n, 12, 12, 13 



and 14 mm. one each 5 



Silvery runts under 11.5 mm 16 



Silvery specimens of larger size -11.5-13. 5 mm 7 



14, 16, and 18 mm. one each 3 



All but two of the small ones had a poorly formed mouth. 



Killed May 7 31 



(c) April 12. 51 operated. Of these, 8 were used for ex- 

 periment 17. Of the remaining 43, two died on April 29; one 

 on the 3Oth and then the mortality became very marked so much 

 so that 31 died in the succeeding 5 days. On May 5 the remaining 

 9 were preserved. They had lived 23 days. These were kept in 

 city water in roomy kitchen sink aquaria from April 18 on. The 

 high mortality in comparison with that of lot 14 (6) is really very 

 striking. 



No. ij. April 12 hypophysis removed, April 13 thyroid also 

 removed. Kept throughout in a glass bowl aquarium in soft 

 cistern water. At the end of 31 days two were dead, the re- 

 mainder were killed. Of these killed May 13, 5 were light and I 

 dark. 



No, IQ. April 14. Length at time of operation 5 and 6 mm. 

 21 operated. The operation was performed upon specimens too 

 far advanced. They showed a high rate of mortality and were 

 soon discarded. 



No. 22. April 20. Stage at operation varied 3.5-4.5. 40 

 operated. Two died soon after. Divided into two lots of 19 

 each. Lot (a) was kept as before, in lot (b) the thyroid gland 

 was also removed. 



In Lot (a) 3 dead by May I. 



In Lot (b~) 3 dead by May 3. 



All dead in few succeeding days. Data not complete. On 

 April 28 both (a) and (6) equally showed the characteristic color 

 change due to removal of the hypophysis proving that this is not 

 due to any lack of balance between these two glands. 



Controls kept in same sink showed no mortality. 



No. 23. April 22. Stage of operation 3.5-4 mm. 42 oper- 

 a,ted. Great care was exercised to avoid injury to the brain. 



