51 
Ordinary Meeting, December 28th, 1869. 
J. P. Joule, LL.D., F.R.S., &c., President, in the Chair. 
“ On Pollen ; considered as an Aid in the Differentiation 
of Species,” by Charles Bailey, Esq. 
Having recently examined the pollen of several thousand 
species of plants, I am led to think that the characters pre- 
sented by these grains might prove useful as a means of 
differentiation in allied species; my researches, however, 
have not been sufficiently extensive to form any positive 
conclusions, but as leisure permits I hope to prosecute the 
subject further. In the meanwhile the following notes are 
thrown out as indications of some of the more noticeable 
distinctions to be drawn from a careful comparison of these 
organs, and they may serve to draw the 'attention of others 
to the matter. 
There are four points, in one or other of which pollen 
grains of plants belonging to the same genus may be found 
to differ from each other, viz., form, markings, dimensions, 
and colour. 
1. Form. It has long been noticed that certain types of 
pollen are characteristic of the natural order to which the 
plants which produce them belong, as for instance, the 
peculiar pitted polyhedral pollen of the Caryophyl'acece , the 
spherical spiny pollen of the Malvacece , the large triangular 
pollen of the Onagracece, the peculiar pollen of the 
Coniferoe, or the elliptical pollen of the Liliciceoc and 
other monocotyledonous orders; in fact, most orders 
possess a type sufficiently marked to be character- 
istic of each. This statement, however, must be accepted 
with limitations ; the Compositce, for instance, have three or 
more well-marked types, represented by the beautifully 
sculptured pollen of the Chicory, the minute oval spiny 
pollen of the Asters, Calendulas, Cacalias, &c., and another 
form wholly destitute of spines as in the Centaurea Scar 
Proceedings — Lit. & Phil. Society. — Y ol. IX. — No. 7. — Session 1869-70. 
