THE SMITHSONIAN INSTITUTION. lOo 



vegetables. Not merely the movement of the fluids of plants within 

 their cells, which has at least some analogy with the motion of ani- 

 mal fluids; but in such plants as the Sensitive plant, the Veuus's 

 Flytrap, (Dioncea,) and many others, movements of the limbs (sliall I 

 call them ?) as singular as those of the Alg;e spores, are sufficiently 

 well known. And these movements are affected bv narcotics in a 

 manner strikingly similar to the operation of similar agents on the 

 nervous system of animals. The common sensitive plant, indeed, 

 only shrinks from the touch, but in the Desmodmm gyrans, a move- 

 ment of the leaves on their petioles is habitually kept up, as if the 

 plant were fanning itself continually. Such vegetable movements as 

 these strike us by their rapidity, but others of a like nature only 

 escape us by their slowness. Thus, the opening of the leaves of many 

 plants in sunlight, and their closing regularly in the evening in sleep ; 

 the constant turning of the growing points towards the strongest 

 light, and other changes in position of various organs, are all vege- 

 table movements, which would appear as voluntary as those of the 

 Alga3 spores, if they were equally rapid. Their extreme slownoss 

 alone conceals their true nature. 



So, then, we find animals in which motion is reduced almost to a 

 nullity, and vegetables as high in the scale as the Legumiyiosce, ex- 

 hibiting well-marked movements — facts which sufficiently establish 

 the truth of our position, that mere motion is no proof of animality. 

 But subtracting their movements from the Alga3 spores, what other 

 proof remains of their being animalcules? None whatever. They 

 do not resemble animalcules, either in their internal structure, their 

 chemical composition, or their manner of feeding ; and their vegetable 

 nature is sufficiently marked by their decomposing carbonic acid, 

 giving out oxygen in sunlight, and containing starch. 



In the Vaucheria clavata, one of the species in which spores moved 

 by cilia were first observed, the spore is formed at the apices of the 

 branches. The frond in this plant is a cylindrical, branching cell, 

 filled with a dense, green endochrome. A portion of the contained 

 endochrome immediately at the tips separates from that which fills 

 the remainder of the branch ; a dissepiment is formed, and that por- 

 tion cut off from the rest gradually consolidates into a spore, while 

 the membranous tube enlarges to admit of its growth. The young 

 spore soon becomes elliptical, and at length, being clothed with a 

 skin and ready for emission, it escapes through an opening then 

 formed at the summit of the branch. The whole surflice of the spore, 

 when emitted, is seen to be clothed with vibratile cilia, whose vibra- 

 tions propel it through the water until it reaches a place suitable for 

 germination. The cilia then disappear, and the spore becoming qui- 

 escent, at length develops into a branching cell like its parent. The 

 history of other moving spores is very similar, the cilia, however, 

 varying much in number in different species. Commonly there are 

 only two, which are sometimes inserted as a pair, at one end of the 

 spore, but in other cases placed one at each end. 



There are other Alga3 in which vibratile cilia have not been observ- 

 ed, but which yet have very agile movements. Among these the 

 most remarkable are the Oscillatorice and their allies, which suldenly 



