36 FEEDING ANIMALS. 



then evaporated, a substance resembling gum arable is 

 obtained. And, according to Schleiden, the fibre may be 

 seen,*under the microscope, gradually to change from with- 

 out inwards, first into starch, then into gum. The fibre of 

 wood or linen may be changed directly into sugar by the 

 prolonged action of dilute sulphuric acid. 



DIGESTIBILITY or CELLULOSE. Woody fibre was form- 

 erly thought to be quite indigestible. Haubner, about 

 1850, showed that ruminants digested a large proportion 

 of cellulose. And hundreds of digestion experiments have 

 shown that this substance is an important part of fodder 

 for herbivorous domestic animals. The German experi- 

 ments have undertaken to fix the percentage of cellulose 

 digested in a large number of our coarse fodders, and also 

 of cereal grains. Of the former, ruminants were found to 

 digest from 30 to 70 per cent., whilst the cellulose of grains 

 was found less digestible. The woody fibre of young and 

 tender plants was found much more digestible than when 

 nearer maturity, and more lignin had formed. It is 

 doubted even now if lignin is digestible, especially in its 

 crude state. 



Starch. This is one of the most abundant substances in 

 the vegetable kingdom, being found in all plants. It is 

 exceeded in quantity only by cellulose. It is supposed to 

 be formed in the green leaves of plants and trees from the 

 carbonic acid of the air, aided by sunlight. It seems to be 

 deposited most rapidly in plants near the time of ripening. 

 It is found largely in the cereal grains. Indian corn con- 

 tains 60 to 68 per cent., and wheat from 62 to 72 per cent. 



Starch appears to the eye like particles of meal, yet 

 under a strong microscope it is found to consist of small 

 and regular grains or globules. 



We have seen how starch may be separated from wheat 

 or other grain. If fresh plants, such as grass before bios- 



