in organic and inorganic Bodies. 163 



servation, that they arose neither from currents in the fluid, nor 

 from its gradual evaporation, but belonged to the particle itself. 



Grains of pollen of the same plant taken from antherae im- 

 mediately after bursting, contained similar subcylindrical par- 

 ticles, in reduced numbers however, and mixed with other 

 particles, at least as numerous, of much smaller size, ap- 

 parently spherical, and in rapid oscillatory motion. 



These smaller particles, or Molecules as I shall term them, 

 when first seen, I considered to be some of the cylindrical par- 

 ticles swimming vertically in the fluid. But frequent and care- 

 ful examination lessened my confidence in this supposition ; 

 and on continuing to observe them until the water had entirely 

 evaporated, both the cylindrical particles and spherical mole- 

 cules were found on the stage of the microscope. 



In extending my observations to many other plants of the 

 same natural family, namely Onagrarice, the same general 

 form and similar motions of particles were ascertained to 

 exist, especially in the various species of Oenothera, which I 

 examined. I found also in their grains of pollen taken from 

 the antherae immediately after bursting, a manifest reduction 

 in the proportion of the cylindrical or oblong particles, and 

 a corresponding increase in that of the molecules, in a less 

 remarkable degree, however, than in Clarckia. 



This appearance, or rather the great increase in the number 

 of the molecules, and the reduction in that of the cylindrical 

 particles, before the grain of pollen could possibly have come 

 in contact with the stigma, — were perplexing circumstances 

 in this stage of the inquiry, and certainly not favourable to the 

 supposition of the cylindrical particles acting directly on the 

 ovulum; an opinion which I was inclined to adopt when I first 

 saw them in motion. These circumstances, however, induced 

 me to multiply my observations, and I accordingly examined 

 numerous species of many of the more important and remark- 

 able families of the two great primary divisions of Phaenoga- 

 mous plants. 



In all these plants particles were found, which in the dif- 

 ferent families or genera varied in form from oblong to sphe- 

 rical, having manifest motions similar to those already de- 

 scribed ; except that the change of form in the oval and ob- 

 long particles was generally less obvious than in Onagrarice, 

 and in the spherical particle was in no degree observable*. 



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

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

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

 tion in the middle of each side, so as to divide it into two nearly orbicular 

 portions. 



Y2 In 



