544 



SCIENCE 



[N. S. Vol. XLI. No. 1058 



pectins were chiefly responsible for the yellow- 

 ing of the fiber, since they formed water in- 

 soluble compounds, which remained on the 

 fiber. The analysis of Hebden, however, 

 showed that the calcium fixed on the fiber in 

 the form of calcium salts was decomposed by 

 the following acid treatments, and he explained 

 the presence of the calcium on the fiber after 

 the sour by the formation of a calcium cellu- 

 lose similar to that of soda cellulose. The pos- 

 sibility of the formation of such a cellulose, 

 he believed, was supported by the fact that cot- 

 ton cloth which has been boiled and bleached 

 did not produce as clear and as brilliant a 

 turkey-red as cloth which had been simply 

 boiled, because the former was not in a con- 

 dition to fix calcium. 



As the result of investigation in this line 

 on cloth from different bleacheries, it occurred 

 to us that an analysis of the growing cotton 

 fiber with a view of determining the nitrogen 

 and the fat and wax factors might reveal some 

 points of importance. The determinations 

 were carried out on Durango cotton raised on 

 the United States Experiment Farm, San 

 Antonio, Texas. ^ 



The nitrogen factors were determined by the 

 Kjeldhal-Gunning method, and the fat and 

 wax factors by extracting samples of the fibers 

 first by ether and then by alcohol. Some of 

 the experiments were carried out in duplicates 

 and some in triplicates, and the averages of 

 the determinations were recorded as the final 

 results. The figures given in the table below 

 can only be regarded as approximating the 

 absolute values of the nitrogenous and fatty 

 and waxy constituents of the fiber; for the 

 determination of exact values a much larger 

 number of experiments should be performed. 

 Nevertheless, they show the tendencies of the 

 two factors and have, therefore, significance. 

 The nitrogen determinations were made and 

 recorded beginnings from the 14— 16-day stage 

 up to the 36-38-day stage, whereas the ether 

 and the alcohol extracts were recorded only 

 beginning with the 22-24-day stage, because 



2 We wish to thank Mr. Rowland D. Mead, of 

 the United States Department of Agriculture, for 

 supplying us with the necessary samples of the 

 cotton fibers. 



in the stages previous to this the amount of 

 tannins extracted by both ether and alcohol 

 were much higher than the fats and waxes. 



From the above table it may be seen that 

 the fats and waxes showed neither a gradual 

 increase nor a gradual decrease in their per- 

 centages, and in view of the fact that the fiber 

 was growing, it seems reasonable to suppose 

 that the fatty and waxy substances increased 

 proportionally as did the fiber. We believe 

 that were the numbers of the experiments large 

 enough to give averages approximating the 

 absolute values of the fatty and waxy factors, 

 this point would have been brought out much 

 clearer. But even from the determinations 

 which we can report, it appears that the fats 

 and waxes extended in an even and constant 

 thickness over the fiber. If we accept the 

 view that the function of these substances is 

 to protect the fiber from external influences 

 of weather and disease, that is that they are 

 merely external coats of the fiber, the signif- 

 icance of such a proportional growth ©f these 

 constituents becomes clear. If, however, the 

 fats and waxes are phosphotides taking part 

 in the growth, there would also be a propor- 

 tional increase. The nitrogen figures, on the 

 other hand, show gradual decrease in percent- 

 age with the increase of the age of the fiber. 

 The sudden increase of the factor at the 20-22- 

 day stage as compared with that of the 24r-26- 

 day stage may be due either to a rapid growth 

 of the nitrogenous constituents of the fiber or 

 to the adhering nitrogenous coloring matters 

 of the parts of the boll which surrounded the 



