in Organic and Inorganic Bodies. 361 



generally less obvious than in Onagrariae, and in the spherical 

 particle was in no degree observable*. In a great proportion 

 of these plants I also remarked the same reduction of the larger 

 particles, and a corresponding increase of the molecules after 

 the bursting of the antherae ; the molecule, of apparently uni- 

 form size and form, being then always present ; and in some 

 cases indeed, no other particles were observed, either in this or 

 in any early stage of the secreting organ. 



In many plants belonging to several different families, but 

 especially to Gramineae, the membrane of the grain of pollen is 

 so transparent, that the motion of the larger particles within the 

 entire grain was distinctly visible ; and it was manifest also at 

 the more transparent angles, and in some cases even in the body 

 of the grain in Onagrariae. 



In Asclepiadeae, strictly so called, the mass of pollen filling 

 each cell of the anthera is in no stage separable into distinct 

 grains ; but within, its tesselated or cellular membrane is filled 

 with spherical particles, commonly of two sizes. Both these kinds 

 of particles, when immersed in water, are generally seen in vivid 

 motion ; but the apparent motions of the larger particle might 

 in these cases perhaps be caused by the rapid oscillation of the 

 more numerous molecules. The mass of pollen in this tribe of 

 plants never bursts, but merely connects itself by a determinate 

 point, which is not unfrequently semitransparent, to a process 

 of nearly similar consistence, derived from the gland of the cor- 

 responding angle of the stigma. 



In Periploceae, and in a few Apocineae, the pollen, which in 

 these plants is separable into compound grains filled with sphe- 

 rical moving particles, is applied to processes of the stigma, ana- 

 logous to those of Asclepiadeae. A similar economy exists 

 in Orchideae, in which the pollen masses are always, at least in 

 the early stage, granular ; the grains, whether simple or com- 

 pound, containing minute, nearly spherical particles, but the 

 whole mass being, with a very few exceptions, connected by a 



* In Lolium perenne, however, which I have more recently examined, 

 though the particle was oval and of smaller size than in Onagrariae, this 

 change of form was at least as remarkable, consisting in an equal contraction 

 in the middle of each side, so as to divide it into two nearly orbic\ilar por- 

 tions. 



