340 SPECIAL DIRECTIONS AND 



merely of spores in spore-cases), without any known limit, and with- 

 out any other fecundation than that which occurred at first upon the 

 germinating plantlet. 



664. In Ferns, accordingly, it is not the sporangium that is fer- 

 tilized, still less the spores, but a cell of a peculiar transitory plant- 

 let formed by the germination of a spore. This cell otherwise will not 

 develop at all ; but when thus fecundated, it develops hke a bud, and 

 grows into a plant of indefinite longevity, capable of fructifying by a 

 tYxie parthenogenesis (571) throughout its long existence. This is 

 also known to be the case with Equisetacete ; and the Lycopodia- 

 cens or Club-Mosses and other vascular Cryptogamous Plants are 

 thought to have analogous fecundation, although the details as yet 

 are not well made out. 



CHAPTER XIII. 



OF THE SPONTANEOUS MOVEMENTS AND VITALITY OF PLANTS. 



665. The facts brought to view in the preceding chapter, namely, 

 that either the spores or the fertilizing corpuscles or filaments of 

 most Cryptogamous plants of every order are temporarily endowed 

 with motivity, naturally raises the inquiry whether such phenomena 

 are altogether exceptional in the vegetable kingdom, or whether the 

 power of executing movements is not a genei'al endowment of plants 

 as well as of animals, although in lesser degree. As we pass in re- 

 view the various phenomena exhibited by plants in this respect, and 

 at the same time consider that self-caused motion, internal or exter- 

 nal, or the foculty of directing motion, is a necessary concomitant of 

 life, we shall probably arrive at the conclusion, that this surprising 

 activity of the microscopic spores and spermatozoids of Cryptogamous 

 plants is not altogether anomalous, — that these are merely more 

 vivid manifestations of a power which they share with ordinary vege- 

 tables, — that plants are endowed Avith life no less really than ani- 

 mals, — that the distinction between plants and the lower animals in 

 this respect is one of degree rather than of kind, — and that it is a 

 characteristic of living things to move. 



