Scientific Intelligence. — Botany. 399 



not see them dissolve. " Now, alcohol poured upon water can- 

 not dissolve, at least instantaneously, drops of resin, as every 

 one knows who has been accustomed to make experiments of 

 this kind. Moreover, it then produces .so violent a microscopic 

 tempest, that it becomes impossible for the observer to distin- 

 guish any thing. In another experiment, the author covered, 

 with a plate of mica, the drop of water in which he had broken 

 a grain of pollen ; but, the plate of mica, at the moment when 

 he placed it upon the drop of water, must have removed from 

 his view the bodies which it fixed ; and, besides, the edges of a 

 plate of mica, which are always ill applied against the object- 

 bearer, cannot, by any means, prevent the evaporation of the 

 fluid, which becomes a powerful cause of automatic motion. 

 We advise the author, when he proceeds anew with such expe- 

 riments, to place a sufficient quantity of water and grains of pol- 

 len in the cavity of a plate of glass, and cover it with another, 

 making the latter slide over the former, without allowing the 

 air to insinuate itself into the cavity. The pollen will burst. 

 The explosion will indeed put the whole in motion, but, in a 

 few moments after, our little automatons will resume the iramo- 

 bihty of all inert globules. I have repeated these experiments 

 a hundred times. Many others have repeated them since ; and 

 M. Brongniart is hitherto the only person who persists in hold- 

 ing so ill-founded an opinion.^ The vague and indeterminate 

 motion, which appears to M. Brongniart so peremptory a proof 

 of the spontaneousness of the corpuscules in question, seems, to 

 M. Raspail, a proof of the contrary opinion ; for any globules 

 of albumen, gluten, starch, and still more of essential oil, sus- 

 pended in water, will present traces of a vague and indetermi- 

 nate motion. " I therefore,'' says M. Raspail in conclusion, 

 ** persist in asserting, that Gleichen's pretended animalcules are 

 nothing, in the malvaceae especially, but resinous drops; and, in 

 other pollens, but inert globules of tissues mixed with these 

 drops.*" M. Raspail concludes his letter with observations res- 

 pecting the comparative value of different microscopes. In his 

 opinion, Jmic?s Microscope (which M. Brongniart employs, and 

 for this reason considers his experiments as peculiarly valuable), 

 is, other things equal, iri/erior to every other microscofK*. Any 

 one having the least knowledge of optics, might convince him- 



