June, 1919] Use of Chicks in Vitamine Tests 



511 



was left unmarked. The marked chicks were selected as the lot 

 for test while the unmarked were kept as' the normal or control 

 chicks. 



As previously stated both lots fed from the same hopper at 

 all times but in addition to this vitamine lacking food the con- 

 trols were allowed to partake once a day of foods containing 

 vitamines; such food was usually a well known commercial 

 ''starting food," although frequently they were given lettuce, 

 milk, apple, etc. The chart presenting the growth curves of the 

 two lots strikingly shows the immediate differences that were 



Typical appearance of the control chicks (left) and of those fed on food low in 



vitamine (right). Photograph taken April 4th, subsequent to 



replacing vitamines in food. 



obtained in the daily average weight of the chicks (the graph 

 does not show the weights for the first two days — which were 

 almost identical). 



One striking feature of the two growth curves is that when 

 the normal chicks gained rapidly (as on March 19, 20, 21) the 

 test chicks likewise show a definite increase, while when the 

 normals' rate of growth slowed down (as on March 22 to 25) 

 the test group failed to gain or even lost weight. The causes of 

 these variations of growth in the controls are yet to be 

 determined. 



