i 9 i S ] HARVEY— ETHYLENE 201 



from (d) — [(&) — (c)] should give an approximate figure for the 

 cellulose present. 



2. Carbohydrates 



Reducing sugars, before and after hydrolysis, were determined 

 for the alcohol-ether soluble fraction. The methods employed 

 were those of Munson and Walker (26, pp. 241-251). The 

 reduced copper was determined by the volumetric permanganate 

 method described in the above-named bulletin (p. 52). Similarly, 

 the reducing sugars were determined for the insoluble fraction after 

 2 . 5 hours of hydrolysis with 3 . 5 per cent HC1. 



3. Nitrogenous substances 



Total nitrogen was determined by the Kjeldahl method and 

 the amino acids and amids by both the formol titration (as described 

 by Jessen-Hansen, 14, and Van Slyke's methods, 34). While 

 employing the latter method, estimations were made of ammonia 

 and alpha-NH, groups both before and after a 24-hour hydrolysis 

 with 20 per cent HC1 at 98-99° C. (see 35). 



4. Fats 



Only the dry weight of the ether extract and the free fatty acid 

 value were estimated. Separate samples were used for fat deter- 

 minations. The tissue was collected and preserved as previously 

 described, but instead of the alcohol extraction being used as before, 

 the tissue was spread out to dry in a current of air, absolute alcohol 

 being added from time to time to hasten the drying process. The 

 dried tissue was then extracted for 12 hours with absolute ether. 

 Also, the preserving liquid was evaporated, the residue dried in 

 vacuo, and taken up with absolute ether. The ether extracts were 

 combined, dried in vacuo, and the weight determined. Free fatty 

 acids of this residue were estimated by titration in the usual manner. 



5. Results 



The following statements are made in explanation of the tables 

 of results. Whenever percentages are given, the figures are always 

 in terms of the total dry weight of the samples. Also, the numbers 

 of the samples are given in order to facilitate proper comparison 



