112 HATCH EXPERIMENT STATION. [Jan. 



producing organs are largely under the control of the nervous 

 system, and any sudden change disturbing the nervous tem- 

 perament of the animal, such as a sudden extreme change of 

 temperature, an angry man, change of milkers, etc., is very 

 likely to have an eifect on the quality of her product. This 

 can easily be observed by testing the milk daily and noting 

 the variations, especially in the percentage of fat. Too short 

 periods render such experiments valueless, as well as changing 

 the entire daily character of the feed in two or three parts of a 

 single experiment. No greater mistake can be made than in 

 employing cheap, unreliable help. The results of many of 

 the experiments thus far made along this line of investigation 

 are of absolutely no value, because one or several improper 

 influences have not been controlled by the experimenter. 



In the two experiments which follow, the experimenter 

 has sought as far as possible to prevent any influence other 

 than the one desired to have any bearing on the results. 

 The methods have been described under A. The complete 

 feeding record of each cow will be found at the end of this 

 article. 



