36 American Quarterly Microscopical Journal. 



frayed and shreddy. In animal fibers, the latter denotes 

 shoddy; in vegetable, paper. Now with a glass rod or medicine 

 dropper allow a little iodine to flow under the cover and the 

 fibers will soon assume a clear light brown. Any surplus 

 should be absorbed by a piece of blotting paper, for with rea- 

 sonable care there is not the least necessity for soiling the stage 

 of your instrument. As soon as the iodine has penetrated apply 

 the sulphuric acid in the same way, and carefully watch the 

 result, comparing it with the annexed table. Several minutes 

 will sometimes elapse before the coloration is complete, and it 

 does not endure for more than a few hours. Bent or creased 

 fibers color more deeply in the flexures, and striae, either longi- 

 tudinal or radial (in sections) will show more plainly as the 

 coloration progresses. In many sorts, of coarser fibers espe- 

 cially, pieces of parenchyma will be seen, that always color yel- 

 low, and may readily be known by their irregular shape. Cross 

 sections can be made with any section cutter by gluing to- 

 gether a little mass of fibers, or bedding them in paraffine, or 

 as often practiced by the writer, rolling them somewhat like a 

 cigarette in a piece of sheet wax such as is used for wax flowers. 

 When cut the mass of mixed sections is placed in benzole or 

 alcohol, when the wax soon floats on top and may be poured 

 off. 



We owe to Vetillart the classification adopted above, which 

 is an important analysis of the reactions of cellulose. The 

 observations in the last column indicate only the prominent 

 characters of each fiber. Mirbel called fiber cells bast cells, a 

 name still used. In Dicotyledons they form the inner layer of 

 the bark, are usually more or less colored, long, supple, and 

 tenacious ; in Monocotyledons they are scattered irregularly 

 through the stem, are white, coarse, light, and often brittle. 

 The central cavity and shape of the ends of the cells are impor- 

 tant features. The blue reaction of Monocotyledons is not so 

 uniform as that of the other classes, quite a large proportion 

 of alfa and esparto also turning yellow; there being apparently 

 two distinct kinds of cells in these plants, which are not mixed 

 indiscriminately in the stem but form separate layers, each of 

 which maintains its characteristic reaction, but becomes inter- 

 mixed in processes of manufacture. 



An inspection of the column headed ratio, will show at once 

 why certain fibers maintain so prominent a place in the indus- 



