These charts bring out the following facts: 
1. The Reichert-Meiss] number and the per cent of soluble fatty acids 
were highest at the beginning of the period of lactation; slight irregu- . 
larities excepted, they decreased as the period of lactation advanced and 
were lowest towards the close of the period of lactation. 
2. The insoluble fatty acids were lowest at the beginning, gradually 
increasing during and were highest at the end of the period of lactation. 
3. The fact that the Reichert-Meiss] Number, the soluble and the 
insoluble fatty acids bear a definite relation to one another shows clearly 
that the per cent of soluble and insoluble acids is affected by the period 
of lactation, and that the soluble acids decrease while the insoluble acids 
increase as the period of lactation advances. 
4. The results concerning the iodine number are irregular, and, con- 
sidering the relatively small number of data, do not warrant the drawing 
of definite conclusions as to the effect of the period of lactation on the 
per cent of olein in butter. 
5. The relation of the per cent of soluble fats and olein to the melt- 
ing point emphasizes that the olein is not the only factor controlling the 
melting point or softness of butter, but that the volatile or soluble fats 
play a part in the determination of the softness of butter. 
