loose one and includes two kinds of chaff, that which 

 immediately encloses the grain (grain-chaff, palets) 

 and that the glumes which subtends the grain with its 

 grain-chaff. This distinction may be readily under- 

 stood by a comparison of oat and wheat. In the oat 

 the grain-chaff (palets) permanently invests the grain, 

 so that after threshing, the "grain" consists of the 

 grain proper plus its chaffy covering of two parts, one 

 larger (outer palet) inclosing the grain, and the other 

 smaller, (the inner palet). The grain of wheat, on the 

 other hand, shells out of the grain-chaff, in which 

 respect rye behaves similarly. Some varieties of 

 barley are like the oat, differing only in the fact that 

 the grain-chaff is firmly attached to the grain. 

 (Harlan, 1918). The structure of these various kinds 

 of chaff differs very widely, so that a full account of 

 all the details would occupy much space. We may 

 note particularly the thin papery character of the inner 

 palet in wheat and rye. Inasmuch as the contribu- 

 tion of chaff to straw is in any event very small, such 

 an account is unnecessary. At the same time, since a 

 certain, if small, amount of chaff is bound to remain 

 attached to straw, and hence may be found in paper, 

 although in exceedingly small proportion, it is advis- 

 able to indicate the general character of the structures 

 which may be found. 



In addition to the chaff, the rachis or that portion 

 of the steam which bears the grain, will contribute a 

 similarly small proportion to straw pulp. The rachis 

 presents equally special conditions of structure, and 

 would call for much detail of description. For this 

 reason also, the following summary of structural char- 

 acters is confined to very general terms. 



Barley. The chaff consists of slender loose parts 

 (glumes) and tlhe bead of the outer palet (lemma). 

 Both palets would be included in straw of hulled 

 varieties. Numerous very thick walled trichomes, 

 strongly oblique in form, give the characteristic 

 roughness of the head of barley. The trichomes of the 

 inner or upper face of the beard are small and thin 

 walled. Cells resembling crown cells occur near the 

 base of the glumes. Crown cells occur locally in small 

 numbers near the apex of the outer palet (lemma), 

 which when adherent, contribute but little to pulp. 



In all the cereals according to Hohnel (1875) the 

 hypodermal cells (bast cells immediately beneath the 

 epidermis) of the thick palets have teeth which arti- 

 culate with corresponding depressions in the epidermal 

 cell walls, and I have verified this. I have not found 

 this condition in the beard. 



Oat. Chaff consisting normally of glumes only. 

 These are thin and leaf-like. The epidermal cell walls 

 are wavy except in the thin papery marginal regions, 

 the cells themselves much shorter than in the leaf. The 

 bearded varieties will contribute trichome cells. 



The palets of unfilled grain with of course an occa- 

 sional filled grain will find their way into pulp. The 

 epidermis is very sinuous and thick walled. There are 

 a few crown cells, which are evidently undeveloped 

 trichomes. They are distinct in appearance from those 

 of wheat because 1 of their somewhat irregular or 

 oblique form. They are quite infrequent. Short, very 

 thick walled trichomes on the outer palet and, along 

 the fold of the inner palet, very numerous trichomes 

 which can be distinguished by their lack of obliquity, 

 standing out as they do at right angles(or nearly so)to 

 the folded edge whence they spring. 



Eye. Glumes and palets, with beard, constitute the 

 chaff. The glumes and outer palet are similar in 

 structure, characterized chiefly by large thick walled 



curved trichomes placed along the fold. The inner palet 

 papery, the epidermal cells thin walled except toward 

 the base, and thin walled crown cells numerous. These 

 are readily distinguishable. The walls of the epider- 

 mal cells, especially those between the stomata very 

 sinuous. 



Wheat. Glumes and palets are the chaff. Very 

 thick walled epidermis and trichomes characterize the 

 glumes and outer palet. The thin papery margins of 

 the inner palet has numerous rather slender trichomes 

 arising from cells, which, as such, are very numerous 

 and have the same appearance as those of the leaf. 



The dwarf cells in all the foregoing generally con- 

 sist as elsewhere of a larger crescentic thinner walled 

 cell and a smaller very thick-walled cell. More ex- 

 ceptionally the dwarf cells occur singly, especially, 

 for example, in the epidermis of the beard of barley. 

 These do not in any event afford distinguishing char- 

 acters. 



It will thus be seen that crown cells, which would 

 occur only in wheat straw pulp if the chaff were ex- 

 cluded, may otherwise be found also in oat and rye 

 straw pulp. Even barley is not certainly excluded on 

 this score. Trichomes, which would be found only in 

 rye and wheat straw pulp, chaff excluded, may other- 

 wise be found in all. The chief purpose of these addi- 

 tional notes therefor is to show the necessity of close 

 study in the event that strict identification is desired. 



Literature. 

 1865. Wiesner, J. Microscopische Erkennung der 



Stroh in Espartopapiere. Wochenschrift der 



Niederoesterreichschen Gewerbevereins. Vol. 



26: 534. 

 1867. Wiesner, J. Technische Microscopic, (p. 96). 

 1870. Duval-Jouve, M. J. Etude anatomique de quel- 



ques Graminees. Mem. Acad. Sci. Montpellier, 



vol. 7, 309. 

 1875. Hoehnel, F. Ueber eine eigenthumliche Ver- 



bindung etc. Wissenschaftliche-praktische Un- 



tersuchungen auf den Gebieten des Pflanzen- 



baues. vol. 1, 149; 162. Vienna. 

 1887. Hoehnel, F. Die Microscopie der technisch ver- 



wendeten Faserstoffe. Vienna and Leipzig. 



2d. ed. 

 1900. Wiesner, J. Die Rohstoffe des Pflanzenreiches. 



2d. ed. Vienna. 

 1900. Hanausek, T. F. Technische Microscopie. (p.106). 

 1906. Chrysler, M. A. The nodes of grasses. Botan- 

 ical Gazette, vol. 41. 1-16, Jan. 

 1909. Haberlandt, G. Physiologische Pflanzenanato- 



mie. 2d. ed. 

 1911. Wehmer, C. Die Pflanzenstoffe. Jena. 

 1915. Brand, C. J. and Merrill, J. L. Zacaton as a 



paper-making material. Bull. 309, U. S. Dept. 



Agri. 4 Nov. 



1917. Carrier, Lyman. The Identification of Grasses 

 by their Vegetative Characters. Bull. 461, IT. S. 

 Dept. Agri. 19 Jan. 



1918. Harlan, H. V. The Identification of the Varie- 

 ties of Barley. Bull. 622, U. S. Dept. Agri. 



1920. (Ommanney, G .G.) Manufacture of Paper Pulp 

 from Flax Straw. Pulp and Paper Magazine. 

 Vol. 18 : 345-350. 1. Apr. (Contains illustrations 

 of flax fibers both in pulp and in paper of in- 

 terest for comparison.) 



1921. Griffin, Martin L. The Renaissance of Straw 

 Pulp and Paper. Pulp and Paper Mag. 19 : 899- 

 900. 1 Sept. 1921. "The yield from straw is 

 from 75 per cent down to 40 per cent depending 

 upon the cleanliness of the resulting fiber." 



