309 



Literary and Philosophical Society of Manchester. 

 Ordinary Meeting, December 2Sth, 1869. 



J. P. Joule, LL.D., P.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 spe- 

 cies of plants, I am led to think that the characters presented by 

 these grains might prove useful as a means of differentiation in 

 allied species ; my researches, hovrever, 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 polyhe- 

 dral pollen of the Cmyoj)hi/llacece, the spherical spiny pollen of 

 the Malvacece, the large triangular pollen of the Onagracece, the 

 peculiar pollen of the Goniferce, or the elliptical pollen of the 

 LiliacecB and other monocotyledonous orders ; in fact, most orders 

 possess a type sufficiently marked to be characteristic 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 Cen- 

 taurea Scahiosa. There are, besides, other natural orders where 

 similar variety occurs. 



But differences of form are met with in plants of the same genus, 

 by which the one species or the other is readily marked off by its 

 pollen ; thus the pollen grain of Anemone sulpJmrea is roundish, 

 but that of Anemone montana is elliptic ; the pollen of Aronicwn 

 Doronicmn is much more elongate than that oi A. scorjjioides ; 

 and while the grains of Ranuncuhcs philonotis are round and yel- 

 low, those of H. platanifolius are elliptic, white and smaller. 



2. Markings. Here again there is endless diversity, and a 

 boundless field lies open for the researches of tired- out dot and. 

 line hunters of diatom-valves. A few instances only of the more 

 striking differences can be given here. 



The pollen of the Geraniaceie and Campanulacece is for the most 



