362 Mary Davies Swartz, 



necessity of drawing our final conclusions only from exact metabolism 

 experiments. The soluble hemicelluloses show great diversity of 

 behavior in the alimentary tract, although equally resistant to diges- 

 tive enzymes in vitro; some disappear entirely, others reappear in the 

 faeces in varying degree, up to 100 per cent. It is evident that the 

 latter do not constitute a source of energy for the organism: how far 

 the former actually do so, remains to be demonstrated. 



