MICROSCOPIC INVESTIGATION. 



19; 



ground to a fine pulp, the cells, viewed with a oue-eighth object-glass, 

 will be magnified to about three-fourths of au inch in length. They are 

 perfectlj^ transparent and are seen to be banded near their centers. 

 The cotton thread or fiber is supposed to be a fiat ribbon, although, 

 v/hen examining several sections of the roots of the fibers, I was con- 

 vinced that the fiber is a flat tube resembling a ribbon. The twist- 

 ing tendency of the cotton fiber is well known, its flat shape fiivor- 

 ing that tendency. If the fibers, when growing or passing from their 

 cells, obey the law which regulates the motion of liquids, as pointetl out, 

 we can account in a measure for their twisting, and as the spiral forms 

 of Avater issuing from an orifice are regulated by the pressure of 

 water and shape of orifice, so may the tendency of the cotton fiber 

 to twist depend on the pressure of the circulating fluids. The experi- 

 ments of Hales and Burcks show that the pressure of the ascending 

 vine-sap is sometimes so gTcat that it will raise a column of mercury 38 

 inches. The pressure of the ascending sap of the cotton plant has not 

 yet been examined. The ranker the growth, theoretically, the greater 

 will be the tendency of the fiber to twist. 



A series of microscopic investigations on cotton of various growths, 

 quick and slow growing, might lead to some practical and valuable 

 results. In the mean time I would suggest, as the most effectual rem- 

 edy, the frequent renewal of the seed in the Fiji Islands. 



Mr. Brower has notified the Department that he will take with him 

 to Fiji, on his return, a quantity of iresh sea-island cotton seed, for the 

 imrpose of experiment as above suggested, and will report the re- 

 sults. 



ONION-BLIGHT AND SMUT— (G^eji».s ^yeronospora.) 



About the middle of August last I was invited by Mr. Benjamin P. 

 Ware, of Swa^mpscott, Massachusetts, to inspect a field near his farm, 

 consisting of four acres of -onions, which were badly blighted with fungi. 

 The ground had been cultivated in the usual manner, and prime seed 

 was used. At an early stage of their growth it was discovered that the 

 onion fungus had dift'used itself so generally over the field that it was 



deemed useless to cultivate 

 it further. In the plot we 

 found remnants of the crop, 

 but very few onions had es- 

 caped the blight. The crop 

 was practically consumed, 

 causing a loss to the propri- 

 etor of about 82,000. I se- 

 lected a few specimens of the 

 blighted onions for exi)eri- 

 ment. The blight is first 

 observed at the base of the 

 leaves as a white mold, which 

 ultimately spreads over the 

 bulb, gradually blackening 

 the surface, and penetrating 

 through the layers. When a 

 portion of the white mold 

 found on the leaf is trans- 

 ferred to the microscopic 

 slide, and viewed by a power 

 1, Fig. 29. The spores seen 



