668 



SCIENCE PROGRESS 



it cannot be greater than ioo. In the case of the ox (Table III) the increase 

 contained 94*5 per cent, of fat. In the other cases it contained less fat but 

 comprised considerable amounts of protein tissue in which 3 or 4 parts of water 

 are associated with 1 of dry matter. 



Formation of protein tissue is involved in the processes of growth. In fully 

 grown animals it occurs only when they are in very low condition ; it is gradually 

 arrested as the condition improves and finally ceases altogether. Any increase 

 beyond this point consists entirely of pure fat. For present purposes the 

 condition at this stage may be called the par condition. 



Normally, growth implies the formation of fatty as well as of protein tissues. 

 The ratio between these may or may not be altered. In other words, growth 

 may take place without alteration of condition, or it may be accompanied by a 

 relative gain or loss of fat. 



Growth and fattening may take place simultaneously or successively. In the 

 latter case the composition of the increase depends upon the amount of increase 

 considered. For example, suppose an animal, containing 20 per cent, of fat, to 

 increase from 100 lb. to 1,050 lb. without change of condition, and that, when it 

 reaches 1,200 lb., it contains 30 per cent, of fat ; the increase, if reckoned from 

 1,050 to 1,200 lb., contains 100 per cent, of fat, but if reckoned from 1,000 lb. to 

 1,200 lb. it contains only 80 per cent., if reckoned from 900 lb. to 1,200 lb. only 

 60 per cent., and so on. 



When growth and fattening take place simultaneously the case is similar. 

 When there is no growth the increase consists entirely of fat. When there is no 

 fattening the composition of the increase is the same as that of the original body. 

 In any other case the composition of the increase depends upon the relative 

 amounts of growth and fattening. 



In young animals not below " par " condition, the whole of the non-fatty matter 

 of the inciease must be attributed to growth; and the amount of this non-fatty 

 matter, plus fat in the same ratio as in the lean animal, gives the amount of the 

 increase due to growth. The difference between the total increase and that due 

 to growth is, of course, the true fattening increase. If the two parts be designated 

 by F and G respectively, then : 



F = m[i - 1°°^) and G = ^ IO °-f> 

 v. 100 - / / 100 - f 



m. 



The amounts of growth and true fattening increase, calculated by these 

 formulas from the data in Table I, are as follows : 



Growth ..... 



Fattening 



Total increase .... 



Same per 100 original weight : 



Growth 



Fattening 



Total increase .... 



Same per cent, of total increase 



Growth ..... 

 Fattening 



Ox. 



lb. 

 14-I 

 188-9 

 203"0 



Pig. 



lb. 

 42-85 

 45-64 

 88-49 



Fat 

 sheep. 



lb. 



4-42 



19-41 



23"83 



Extra-fat 

 sheep. 



7-0 



93 "o 



48-4 

 51-6 



18-5 



81-5 



lb. 

 71-25 



72-57 

 143-82 



74'9 



75'° 



150-5 



497 

 5°'3 



