20 DireEctToR’s REPORT OF THE 
Experiments indicated that, when peach trees were less than 
five years old, a severe pruning or cutting back to large limbs was 
a successful method of treating injured trees. The same treat- 
ment for older trees was a failure. Trees that did not carry any 
fruit made a better recovery than those that carried even a light 
crop. 
DEPARTMENT OF CHEMISTRY. 
Some of the relations of casein and paracasein to bases and 
acids, and their application to cheddar cheese.—The relation of 
milk-casein to the cheese industry is one of fundamental 
importance, and the changes takimg place in the processes 
of cheese-making and cheese-curing can be understood fully only 
by a careful study of milk-casein. Bulletin 261 had for its object 
such a study of milk-casein. Casein exists in milk as a com- 
pound with calcium, containing about 1.5 per ect. of calcium 
oxide (lime). When treated with acids, the lime is removed from 
combination with casein and free casein is formed, which is soluble 
in 5 per ct. salt solution and in hot 50 per ct. alcohol. When 
free casein is treated with acid, it forms a casein salt of the acid; 
casein lactate, for example, is familiar in curdled sour milk as the 
white solid or curd. When milk-casein is coagulated by rennet, 
as in cheese-making, the curd formed is calcium paracasein, which 
changes, in the presence of the acid formed in the cheese-making 
process, into free paracasein, and it is this compound that the 
cheese-maker aims to produce in as large amounts as possible 
in the cheese-curd before putting it in press. It is this free para- 
casein that forms the starting point of the various complex 
changes that take place in cheese-ripening. 
The proieids o7 butter in relation to mottled butter.—- 
Butter-makers are frequently troubled by the presence of 
white streaks and spots in butter, which do not make their ap- 
pearance until the day following the packing of the butter. This 
trouble has commonly been attributed entirely to the uneven dis- 
tribution of salt in butter. The werk reported in Bulletin 263 
shows that the presence of buttermilk in butter is essential to the 
production of mottles. The casein lactate contained in butter- 
milk is acted upon by salt, whether the salt is evenly distributed 
or not, and white masses result when buttermilk is present to too 
ereat an extent in the butter granules. It was found that mot- 
