Geology and Natural History. 493 
whole exterior flesh as calyx, Prof. Decaisne (no doubt correctly) 
regards it as mainly receptacle or axis,—an hypanthium which in 
common pears is largely a hypertrophy of the peduncle, after the 
fashion of Anacardium. 
In the proper Pear genus, the ovules never exceed a single 
pair; this should therefore enter into the generic character. 
‘Theophrastus had already remarked that the older the Pear 
tree, the more prolific, and every day’s experience confirms the 
The gritty grains or lignified cells 
which are so abundant in the flesh of many sorts of pears are not 
wholly absent from ay of them. To them is due the roughish 
surface of the skin, as contrasted with the smooth skin of a ples. 
is curious to remark that Meyen, in his Pflanzen-Pathologie, 
considered the gritty grains to be a disease which attacked pears 
and quinces. 
mal size by supporting the growing pear from underneath, instead 
of ae it to hang on the a pear M. Decaisne has seen 
mucilaginon, except of a Photinia, in which it is reticulated. The 
cotyledons are accumbent relative to the rhaphe, et by in a Pho- 
tinia, ciaanater Pyracantha ( Crategus Pyracantha Pers.), and 
Eriobo a@, in which they are incumbent. At first there is a thin 
layer of albumen, which disappears at maturity of the seed. 
are commonly grafted upon a Quince stock. But it is 
confidently asserted, and generally supposed, that there are more 
ut, 
as Prof. Decaisne Bia horticulturists are too apt to get 
: . re 
with the quince stock. He naturally Ty Dave assertion made 
survived at least six years, but without vigor, and bore fruit il 
this antipathy confirms the generic difference between Pyrus an . 
alus, 
