24 Director's Report of the 



or mineral matter which they contained. Bone ash was found to 

 supply a deficiency existing in most rations which consisted wholly 

 of grain and other vegetable foods. 



In order to get further intimation as to the extent that the inor- 

 ganic material was of nutritive value and how much of the benefit 

 from its use might be due to mechanical assistance, certain other 

 feeding experiments have been made. 



In these tests nineteen lots of chicks were fed for either ten or 

 twelve weeks, beginning with chicks from one to three weeks old. 



The mixing of sand in the food, both in a ration containing animal 

 food and one without, results in better health for the chicks and more 

 efficient use of the food. The advantage of the sand was most ap- 

 parent during the first four weeks. 



The addition of raw ground Florida rock phosphate and sand to 

 rations both with and without animal food resulted in better growth 

 and more efificient use of food than when sand alone was added. 



The addition of the ground rock to rations without animal food 

 resulted in more rapid growth and more efficient use of food than 

 the addition of sand alone. 



Ground rock phosphate proved a better addition to rations both 

 with and without animal food, than ground oyster shell. Better 

 growth resulted and, on the whole, from less food. 



Food mixed with finely ground oyster shell was less healthful and 

 less efficient than when mixed with fine sand. 



Mixing bone ash and ground oyster shell in the food resulted in 

 more rapid growth than the mixing of sand alone, but injury attri- 

 buted to the ground oyster shell made the feeding less profitable. 



DEPARTMENT OF BACTERIOLOGY. 



Black rot of cabbage and cauliflower. — This trouble has been 

 studied in cooperation with the Botanical Department. The treat- 

 ment by removing all diseased leaves which has been recommended 



