356 



Mary Davies Sivartz, 



The coefficients of digestibility of the salep preparations are shown 

 in the following table: 



SERIES C. 

 EXPERIMENT NO. 



COEFFICIENT OF DIGESTIBILITY. 



For the Dog. 



For Man. 



Thus we see that in every case, except that in which a dog received, 

 in one day, 10 grams of pure mannan, the greater portion of the salep 

 fed was digested, the coefficient of salep powder for dogs averaging 

 85 per cent, and for man, 97 per cent; while that of pure mannan for 

 man is 100 per cent, in spite of the fact that it is not attacked by diges- 

 tive enzymes! 



The contrast between the volume of faeces produced when a galac- 

 tan such as Irish moss was fed, and that when a more digestible hemi- 

 cellulose was given, is shown in the photograph of the faeces from 

 experiments Nos. 1 and 2 of Series C,^ on the next page, in which A 

 represents the fore-period, B the mid-period, and C the after-period, 

 each period being three days in duration. The group on the right 

 represents experiment No. 1, in which 70 per cent of the hemicellulose 

 and starch of the salep powder was digested, and that on the left, 

 experiment No. 2 in which apparently all of these were digested. 



DISCUSSION AND SUMMARY. 



A glance at the table on page 327 clearly shows that none of the 

 hemicelluloses under consideration are readily attacked by the ordi- 

 nary animal or vegetable enzymes. The results are for the most part 

 entirely negative. Even where there has been hydrolysis with 0.2 

 per cent hydrochloric acid, the amount of sugar produced in 24 hours 

 was relatively small. The hydrolyzing action of the gastric juice 

 is probably largely due to the presence of acid, although no compari- 

 son of the relative amounts of sugar produced by gastric juice or by 



^Cf. p. 348. 



