472 
EDWARD F. WOODCOCK 
gonaceae among the families characterized by perisperm containing 
seeds and curved embryos, comprising the Caryophyllaceae, Parony- 
chiaceae, Portulaceae, Phytolaccaceae, Sclerenthaceae, Chenopodi- 
aceae, Amaranthaceae, and Nyctaginaceae. In discussing the Cur- 
vembryeae, Harz states that he finds without exception in all the 
species studied an oily endosperm in slight amounts laid down about 
the axis of the embryo so that the radicle is surrounded by an endo- 
sperm sheath. The observations of the writer show that this structure 
noted by Harz is not so specialized a character as he implies, but rather 
represents the micropylar portion of the aleurone layer which is also 
continuous to the chalazal region of the seed. 
Since the Polygonaceae are characterized by an abundant endo- 
sperm instead of perisperm as believed by early writers, there cannot 
be the close relationship between the Piperaceae and Polygonaceae 
that Johnson (ii, 1902) suggests. 
In his work on Seedlings, Lubbock (14) has followed the classifica- 
tion given by Bentham and Hooker and correctly interpreted the 
storage tissue in the seed of Polygonaceae as endosperm. Neither in 
the Polygonaceae nor in any of the other families which he included 
under the Curvembryeae does he refer to the aleurone layer of the 
endosperm or to the perisperm. 
Among the Dicotyledons having a curved embryo and endosperm, 
the Nolanaceae, Solanaceae, Resedaceae and Convolvulaceae may be 
mentioned, but in each case there are other more prominent characters 
which cannot be overlooked and prevent them from being considered 
close relatives of the Polygonaceae. 
The variations in the morphology of the Polygonaceae seed would 
seexH to snow that this family represents a more or less plastic evolu- 
tionary line. A primitive character is seen in case of the median 
embryo of Rheum and Fagopyrum, and a marked advance over this 
type in the curved embryo of Polygonum, Polygonella and Rumex. 
The orthotropous ovule prevailing in this family is also a primitive 
character. If some of the other characters of the Polygonaceae, as 
the wings developed on the fruit of Rheum, and the ochrea or tubular 
stipule occurring all through the family, are taken into consideration 
it is very evident that there has occurred some very high specialization. 
Summary 
The outermost layer of the nucellus becomes transformed into a 
nutritive jacket at some period before fertilization. This layer ap- 
