NUTRITION AND GROWTH OF LARVAE 155 



Amino aclda for growth and differentiation of Anura : (Gudematach & Hoffman, I956)* 

 Glycine "] 



Alanine > for maintenance 



Leucine J 



Aspartlc acid 4. j i. j. _i. j j. 



_, . . ., toxic, tut may support maintenance 



Glutamic acid ' 



Arglnlne~ 



lysine [> for grovrth 



Cystine 



Phenylalanine"] 



Tyrosine > for differentiation 



Tryptophane J 



_ .. toxic hut may support differentiation 



Proline 



(* Note: The hest acid of each group Is In the lowest, or most advanced position. 

 Most of these acids are expensive, and their use in experimental analysis 

 of protein nutrition is prohititlve, hut the paper hy Gudematsch and 

 Hoffman should be studied for its J~emarkahle findings.) 



METHOD: 



Precautions : 



1. Any food, particularly those which become acidic, will be a source of bacterial 

 contamination. It will be necessary therefore to change the culture medium, and 

 add fresh food on alternate days at first, and finally, every day. 



2. Overfeeding is not possible, but maximal feeding will be achieved only by pro- 

 viding excess food. Experience alone will determine for any group of tadpoles 

 the amount of food which is Just in excess of maximal. 



5. Green vegetables must be washed to free them of arsenic used by gardeners to get 

 rid of Insects. 



Control : A variety of foods should be tried, and that which provides the most rapid 

 and normal growth may be considered the control diet. All other conditions of space, 

 medium, light, teniperature, etc. must be the same for all embryos. 



Procedure : 



1. Provide uniform containers, each with a measured volume of the culture medium. 

 Begulation finger bowls holding 5 tadpoles or Urodele larvae and 50 cc. of medium 

 will prove satisfactory. The large (12 inch) crystallizing dishes may be used 

 with 50 tadpoles and 100 cc. of medium. Mark the containers adequately, and 

 place them in a uniform environment. The temperature should be about l4°-l8°C. 

 for Urodeles and about 5°C. higher for the Anura. 



2. Select three distinctly different diets, such as carbohydrate, protein, and some 

 synthetic mixture for comparison. Set up at least 5 finger bowls (or 2 crystal- 

 lizing dishes) for each diet offered, using a minimum of 25 tadpoles (or larvae) 

 for each diet. 



5. The larvae may be carried to and through metamorphosis (Anura) which takes from 

 2^ months to longer, depending upon temperature, space, and food. In this ex- 

 periment, with temperature and space controlled, the emergence of the forelimb 

 can be regarded as the beginning of metamorphosis and a terminal point for the 

 nutrition experiment. 



OBSERVATIONS AND EXPERIMENTAL DA^A : 



Growth measurements should be taken at weekly Intervals to determine the relative 

 value at different stages of the different nutritional offerings. These readings may be 

 taken rapidly by placing a piece of calibrated graph paper beneath a Petri dish, axid the 

 tadpoles transferred to this dish for direct size readings. 



