POLLEN. 85 



inner the intinCy wliich is very extensible and exceedingly 

 thin. Tliis may l)e exhibited by placing some pollen in very 

 dilute sulplimic acid and instead of bursting as in tlic cnse men- 

 tionod in the j>rcceding paragraph, projections will be seen 

 to arise t'roin tho stirfareot* the grain and extend into the lluid. 

 These lengthen till the contents of the granule are exhausted 

 and consist of the intine projecting through the coat of the ex- 

 tine. Hv the sulphuric acid many tubes nre projected from the 

 same grain, naturally only one or two. Two otiier coiits have 

 been detected in particular plants, but have not yet been de- 

 monstrated as a common structure; the one next the extine, 

 but interior in respect to it is called tho intfxiiic as in the Ona- 

 graccir, the other l>etwecn this and the intine is called the ex- 

 intine, ?nd is found in the Cuprcssus, 



Raspail asserts, and we think with very good reason, that 

 the pollen is a production of the internal surface of cells with- 

 in the theca, to which the grains are attached by a funicle. 

 ChimieOrganique tome ii. p. 172. This is denied by other 

 Botanists. 



99. The color of pollen is generally yellow ; but it as- 

 sumes in ditTerent plants almost every color except green. 

 The matter contained within the pollen cells is called ybr/7/a, 

 which we before remarked consists of minute molecules, mea- 

 suring, according to Lindley, tVom the 4000th to the .30000th 

 of an inch in length, and arc of two kinds, one larger than 

 the other. The larger are proved to be starch, t'rom the blue 

 color given by the action of iodine; the others are by Mohl and 

 Fritzsche considered to be minute drops of oil. When a pol- 

 len cell bursts in a fluid, these molecules are observed to possess 

 a regular rapid motion on their axes, and the larger undergo 

 a kind of '* spasmodic contraction of the side." Much spec- 

 ulation has been elicited in explaining the constitution and 

 function of these molecules ; but as yet very little has been 

 settled as to their nature by any investigations yet published. 

 Brongniart some years since published the singular opinion 

 that the molecules, wiiich issued on the bursting of the pollen, 

 were spermatic animalcules. Fie described the form, dimen- 

 sions, and movements upon which he based this opinion. This 

 announcement called forth much discussion, and the oppo- 

 nents of B. thought their conquest now complete, when they 

 proved that, int'usions known to be fatal to all animalcules, did 

 not arrest the movements of that issuing from tlu> pollen cell. 

 But the distinguishod Professor Maven. of Berlin, in a letter 

 to the Academy of Sciences of Paris, in 1838, says that the 

 molecules are not the animalcules, but that they occupy the 



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