55 



and also mixed with acid. The constituents determined 

 in the food and manure were dry matter, mineral 

 matter, sometimes " woody-fibre," and nitrogen. 



In the case of pigs, individual male animals were ex- 

 perimented upon, each for periods of 3, 5, or 10 days 

 only. Each animal was kept in a frame, preventing it 

 from turning round, and having a zinc bottom with an 

 outlet for the liquid to run into a bottle, and it was 

 watched night and day, and the voidings carefully col- 

 lected as soon as passed. This could easily be done, 

 as the animal never passed either faeces or urine without 

 getting up, and in getting up he rang a bell, and so 

 attracted the notice of the attendant. The constituents 

 determined were, in the food and faeces, dry matter, ash, 

 and nitrogen, and in the urine, dry matter, ash, nitrogen, 

 and urea. 



The loss or expenditure of constituents by respiration 

 and the cutaneous exhalations has not been determined 

 directly, that is by means of a respiration apparatus, but 

 only by difference, that is by calculation founded on the 

 amounts of dry matter, ash, and nitrogen r in the food, 

 and in the (increase) faeces and urine. 



Besides the special experiments which will be 

 presently referred to, made to determine the influence 

 of different foods on the quantity and composition of 

 milk, a careful daily record has been kept for several 

 years, of the morning and evening yield of each in- 

 dividual, of a herd of between 40 and 50 cows, regard 

 being had to the amount of food consumed, which in 

 its turn has been to a certain extent graduated accord- 

 ing to the yield. 



Independently of the points of enquiry above enu- 

 merated, the results obtained in the feeding experiments 

 have supplied data for the consideration of the follow- 

 ing questions : 



1. The sources in the food of the fat produced in the 

 animal body. 



2. The characteristic demands of the animal body 

 (for nitrogenous or non-nitrogenous constituents of 

 food), in the exercise of muscular power. 



