Nutrition Investigations 293 



puppae of Lepidoptera and Diptera. Similar negative results have 

 been obtained with the digestive enzymes of higher animals. Kino- 

 shita (257) found that emulsin and invertin did not hydrolyze the man- 

 nans of Conophalliis konjaku and Gatin (245, 246) tried the blood of 

 rabbits, chicken serum, the pancreatic juice of dogs, the macerated 

 intestines and pancreas of chickens and cattle, upon salep and carob 

 seeds with negative results; on the other hand, Sawamura (268) re- 

 ports a mannanase in the extracts from different sections of the ali- 

 mentary tract of swine and horses. 



DIGESTION AND UTILIZATION BY ANIMALS AND MAN. 



There are also very few records in the literature of feeding experi- 

 ments with mannans. In a paper in the Zeitschrift fiir Biologic, Voit 

 (283) in 18741 described one by Hauber, who fed a medium sized dog 

 390 grams of dry salep powder in the course of eight days. The faeces 

 of the feeding period were roughly marked off, and Hauber reported 

 no unchanged salep present in them, because there was no swelling 

 in water as with the original powder. Calculations based on the yield 

 of sugar from the faeces on hydrolysis showed that at least 50 per cent 

 of the salep was absorbed. This seems to have been a very crude ex- 

 periment, and cannot be considered of convincing value. 



In 1879, Weiske (284) fed carob-beans {Ceralonia siliqua) to sheep, 

 along with meadow hay, and compared the nutritive value of this ra- 

 tion with one in which the carob-beans (210 grams) were replaced by 

 an equivalent weight of starch, sugar and protein (from crushed peas). 

 The coefficients of digestibility and nitrogen balance were so nearly 

 the same on the two rations, that Weiske pronounced "Johannis- 

 brod" (carob beans) an acceptable and digestible feed for sheep. 



In 1890, Schuster and Liebscher (274) tried feeding the sawdust of 

 ivory nut {Phytelepas macrocaypa) to sheep, having previously found 

 that it had a favorable effect on cattle. Merino sheep gained consider- 

 able fat when fed oat straw and vetch fodder, plus ivory nut sawdust 

 furnishing 50 per cent of the digestible carbohydrates. The ration, 

 exclusive of the ivory nut, did not yield enough energy for such a re- 

 sult to be possible, hence the latter must have been utilized. The 

 coefficient of digestibility, both for the nitrogen-free extract and crude 

 fiber of this material, was at the same time shown by Niebling (262) 

 to be 82 per cent for sheep. 



^This paper reviews the early literature on gums. 



