76 



destroyed." Such ii macliine might be of utility where the injury done 

 by grasshoppers "would warrant the expenditure necessary to make it, 

 but iu order to be of much use, it should be constructed so that the 

 insects once swept into the mouth of the machine could not escape 

 again. This might be accomplished by making the opening in front of 

 double cloth, the inner net or bag being much shallower than the outer 

 one, and ending in a small opening into the main bag like a tish-fyke. 

 The insects should then be forceu to pass between the rollers by means 

 of something like a revolving scraper, or they would be very apt to clog 

 up in the hinder end of the machine, and not pass between the rollers 

 at all. For the flying grasshoppers, such as Calopienus sprettis, &c., 

 mentioned in our January report, it might be advisable to use the 

 machine when they are yet in the larva or i)upa state, and before they 

 acquire wings, by means of which they would be able to escape being 

 swept into the mouth of the machine. 



CHEMICAL MEMORANDA. 



BY E. T. BROWN, CHE^nST. 



'J 



An interesting discussion is in x)rogress among the chemists of con- 

 tinental Europe, on the true character of that substance which forms 

 the frame- work of plants, generally known as woody fiber. Chemists 

 have heretofore considered this as a single proximate element, but the 

 researches of Dietrich and Konig have pretty clearly established the com- 

 l^lex character of this substance. There is first the true frame- work, or 

 vegetable fiber, consisting, substantially, of organized starch. To this 

 substance the term cellulose has been appropriated. Covering this true 

 skeleton is found a second substance, much denser than the cellulose, 

 and containing the chief part of the mineral matter remaining as ash 

 after the plant is burned. This is called lignin. These terms have been 

 heretofore applied indiscriminately to woody fiber. 



The point of interest in the discussion lies in the fact that cellulose is 

 largely digestible, while lignin is almost indigestible. Dr. Marcker, 

 at Weende, has conducted a series of instructive experiments on the 

 digestion of hay by sheep. Of the crude fiber of meadow hay he found that 

 about 60 per cent, was digested, and the 40 -pev cent, which remained in 

 the excrement consisted chiefly of the lignin, containing a large propor- 

 tion of the mineral elements of the food. Of the albuminous portion of 

 the hay, but 55 -per cent, was digested, while the non-nitrogenized sub- 

 stance, such as sugar, gum, &c., proved more digestible, 68 per cent, 

 having disappeared. When the experiment was repeated with hay of 

 the second cutting, in which the woody fiber had not fully matured, it 

 was found that 68 per cent, of the crude fiber was digested. Professor 

 E. Wolfit' has made similar experiments with red clover hay, with results 

 almost identical. He ascertained, however, in another experiment, that 

 clover which was cut before it had blossomed was about one-sixth more 

 digestible than that which had passed the bloom before it was cut. 

 From these experiments it is fairly to be inferred that the increased 

 weight which grass acquires in ripening is from the increase of indigest- 

 ible lignin, and not from digestible cellulose. Meadow grass or clover 

 cut at or before blooming is worth 16 per cent, more than an equal 

 weight cut after it has matured. Tbe nutriment in the seed of timothy 



