62 Uviversity of California Puhlications in Zoology [Vol. 11 



were not necessarily lighter colored. A part of the yoUc was 

 removed from a number of tadpoles by .sucking it through a 

 capillary tube. Approximately half of the yolk was removed 

 from the Ea)ia tadpoles and a larger proportion from the Hyla 

 tadpoles. The yolk was not removed until the embryos were 

 quite large — nearly ready to hatch — so it is probable that in the 

 case of Hyla at least, a portion of the alimentary tract was 

 removed with the yolk. 



The two lots of Raiia tadpoles, those from which the yolk had 

 been removed, and the control presented practically the same 

 appearance : both were dark grey, but those which had suffered 

 the loss of yolk were no lighter than the control (table 2). 



Length measurements of tadi)oles from which .yolk has been removed. 

 Measurements represent average lengths of all tadpoles in the dish. 



A. Sana tadpoles. Yolk removed Feb. 2, 1912 



Feb. 26 



Length 1 



Feb, 6 Feb. 9 Feb. 13 Feb. 20 Feb. 26 tadpoles Color 

 Yolk removed 10.3 12..5 13.8 15.0 14.8 8 Medium 

 Control 9.9 12.2 14..5 14.9 14.9 5 Medium 



B. Hyla tadpoles. Yolk removed Feb. 19 



Mar. 2 

 Length measurements in mm. taken ^ 



Number of 



Feb. 20 Feb. 22 Feb. 26 Mar. 2 Color tadpoles 



Yolk removed 7.87 9.08 9.5.5 9.4 A few somewhat 3 



(10 tadpoles) lighter than control 



Control 8.1 9.51 10.15 10.05 Medium 9 



(10 tadpoles) 



Tlie two lots of Hyla tadpoles showed slight differences. Some 

 of the individuals that had suffered the loss of yolk were as dark 

 as the control tadpoles but others were a little lighter. Micro- 

 scopical examination shows that these lighter individuals have 

 about the same number of pigment spots, but that some of the 

 spots are smaller and some are a little lighter than those of 

 the control tadpoles. 



This difference seems to me to be a direct result of the loss 

 of nourishment — the amount of pigment is less just as the length 

 and width measurements are less and the muscles and other 



