108 EXPERIMENT STATION EECOKD. 



and ammonia nitrogen. " Protein nitrogen was precipitated by means of phos- 

 photungstic acicl, the filtrate boiled in an 8 per cent solution of hydrochloric 

 acid and distilled in the presence of an excess of magnesium oxid. In all cases 

 the amount of nitrogen so estimated was insignificant." 



The most important carbohydrate constituent of kelp is algin, obtained by 

 digesting cold for 24 hours with a 2 per cent sodium carbonate solution and 

 precipitating from the filtered extract with dilute hydrochloric acid. The 

 percentage of algin obtained varied from 13 to 24 per cent when calculated on 

 a di-y basis. An exception was Iridcea spp., which only showed 1 per cent of 

 the complex. The composition of a purified, bleached with sulphurous acid, 

 and dried sample of algin was as follows: Nitrogen, 0.3 per cent; ash, 2.2 per 

 cent ; furfurol calculated to pentosans, 38.6 per cent ; and material Insoluble 

 after treatment with concentrated nitric acid (cellulose derivative) 24.5 per 

 cent. Algin is regarded as a very complex resistant compound (or mixture of 

 compounds) of the pentosan type, with cellulose possibly making up a part 

 of the complex. It has weakly acid properties, forming soluble compounds 

 with the alkali metals. The properties of soluble and insoluble alginates are 

 described. 



The carbohydrates in kelp precipitable by alcohol were smaller in quantity 

 than algin, and in M. pyrifcra the stems showed uniformly higher percentages 

 than the leaves. The dried substance contained 1.2 per cent of niti'ogen and 

 yielded furfurol, corresponding to 13.2 per cent of pentosan. No color test 

 was given with iodin and no reduction with Fehling's solution. The moist 

 precipitate when boiled several hours with a 2 per cent solution of sulphuric 

 acid reduces alkaline copper solution considerably. Upon drying, the precipi- 

 tate became very resistant to solution and to hydrolysis. A composite sample 

 of fiber, obtained as in the crude fiber method, was treated by the chlorination 

 method of Cross and Bevan (E. S. R., 28, p. 805) and showed that approxi- 

 mately one-half of the crude fiber, or calculated on the whole dry plant, 3 to 4 

 per cent was composed of pure cellulose. 



Dried kelp when treated with 2 per cent sulphuric acid was very resistant to 

 hydrolysis and yielded copper-reducing substances only with difficulty. Kelp 

 was found to contain a considerable portion of water-insoluble sulphur, which 

 is regarded as organic sulphur. The leaves contained uniformly more sulphur 

 than the stems. Volatile sulphur compounds could not be noted. The iodin 

 of dried kelp was found almost entirely soluble in cold water or in 90 per cent 

 alcohol. 



Although Pacific coast kelps contain an appreciable amount of nitrogen, it 

 is doubtful whether they can be considered an important feeding stuff. Al- 

 though the percentage of acid amid nitrogen is apparently very small, it is 

 necessary to prove that the remainder of the soluble nitrogen is present in the 

 form of suitably proportioned amino acids before a high nutritive value can be 

 assigned to the material. " Furthermore, the nitrogenous compounds would 

 undoubtedly be rendered less available because of the admixture of large 

 percentages of highly resistant polysaccharids." Another factor which must 

 be taken into consideration is that cows will not eat the leached or unleached 

 fresh kelp unless It is well mixed with other feed. " In order to ascertain 

 whether kelp might be preserved in the fresh state as a sort of silage, a sample 

 of 2V. luetkeana was packed in an air-tight container and stored for three 

 months. At the end of this period there was no indication of putrefaction. 

 The acidity had increased slightly, the final percentage being 0.18 as lactic acid. 

 The sample had become .soft and ' crumbly,' but there was no formation of 

 reducing substances or marked increase in soluble material." 



