IOWA ACADEMY OF SCIENCES. 
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same general structure occurs throughout the order. The 
malpighian cells are very characteristic. Haberlandt, Han- 
ausek, Pammel and others have shown that in Phaseolus vulgaris 
twinned or simple crystals occur in the layer immediately fol- 
lowing the malpighian cells. In related species and genera 
these are not found. Harz does not call attention to crystals in 
this layer in Phaseolus multijlorus; and L. H. Pammel, who has 
studied American species like P. lunatus and Stropliosytles pauc- 
ciflorus and S. angulosa has not found crystals in the second 
layer. We may reasonably conclude that for diagonostic pur- 
poses this is a valuable character. 
Very little attention has been given to a study of the seed 
coats of the order Polygonacece. Buckwheat, Fagopyrum esculen- 
tum and F. tartaricum, have been studied for economic reasons 
by Harz, Weisner, Hanausek, Moeller, while Kraus has studied 
not only Fagopyrum, but Polygonum and Rumex. 
In Coccoloha, according to Lindau and Hammer, the seed is 
provided with two integuments. In one the parenchymatous 
portion of the seeds becomes much expanded during growth, 
rifts are found, usually two at each corner; into these the outer 
integument grows; and the parenchyma rapidly develops. 
Harz, in his paper, describes the anatomy of several species 
of the order Polygonacece, especially the economic species 
Fagopyrum esculentum, F. tartaricum and F. rotumlatum, giving 
several excellent figures. Harz also speaks of Rheum which 
has been described by Kraus, but I have not seen this paper. 
Kraus has also studied a specie of Rumex and several species 
of Polygonum. According to this author the outer epidermis of 
the achenium of P. Persicaria consists of long star- shaped, 
thickened cells. The middle portion agrees with Rumex crispus. 
He states that the glistening appearance of these seeds is due 
to the thickened cuticle. Tannin is very abundant in the undevel- 
oped fruit; a little is found in the outer epidermis, but it is 
largely developed immediately underneath; farther in this 
material diminishes. The fruit of P. Hydropijier, P. aviculare, 
P. dumetorum, and P. convolvulus are structurally alike. The 
fruit of P. convolvulus is not shining and is covered with strong, 
irregular one and two- rowed cuticular projections. Harz 
describes seeds of P. tinctorum, but he does not figure the species. 
He states that it resembles Fagopyrum esculentum. 
In the arrangement of the genera and species Gray’s Manual 
has been followed. The different North American genera of 
