Vegetable Physiulogy for the Year 1836. 387 



by Mirbel's beautiful observations on the formation of the 

 pollen in the Cucurbitacece. I myself have often thought I saw 

 in the formation of the glafidulce capitatcc of several plants the 

 origin of septa in the cells ; the peculiarly formed hairs on the 

 internal surface of the sacs in the genus Ulricularia also ap- 

 pear to originate only by contraction, excrescence, and sepa- 

 ration. Nay, even such a formation of more or less complete 

 septa is evident in the diachymous cells of the leaves of Pinus 

 silvestris; they may be seen in diagonal sections as runners 

 from the internal side of the cellular septum; but a complete 

 division of these cells is in truth not to be perceived. 



An increase of vegetable cells by separation has been 

 already proved in a direct manner; and therefore those di- 

 stinctive characters which Ehrenberg* established between 

 animals and vegetables are by no means so conclusive, but 

 might on the contrary be used to prove what Ehrenberg en- 

 deavours to refute. Ehrenberg considers an increase by di- 

 vision as a character which belongs to numerous beings 

 plainly evincing themselves to be animals, and which is to- 

 tally wanting in plants, since the latter always grow by in- 

 creasing in length and the formation of buds ; and that on that 

 account the Bacillarice are not plants, but must be classed with 

 animals. As it has now been proved that the division of cells 

 takes place exactly in the same manner in well-defined plants 

 as in the Bacillarice, and as it can be shown that the separa- 

 tion in the increase of Infusoria and other lower animals is 

 very different from this separation of vegetable cells, such a 

 separation by septa might even furnish a character to di- 

 stinguish vegetables from animals. 



Mohlf observes that the character mentioned by Ehren- 

 berg, viz. the power of separation in animals, the want of it in 

 plants, suffers the fate of various other distinctive characters 

 which have been started separately : in general they are right, but 

 in special and doubtful cases they are not to be depended on. 

 Mohl here refers to his observation on the separation of the 

 conferval sacs, of which we have already spoken. Mohl also 

 confesses that after many years' observation he still remains 

 quite in doubt as to the place which the Bacillaria; should 

 occupy, that however their increasing by separation does not 

 justify us in classing them as animals. 



* Memoir read before the Academy of Berlin 25th of April. Ulnsiitut, 

 p. 195. Also Scientific Memoirs, vol.i. p. 405. 



f On a Character for distinguishing Animals and Plants proposed by 

 Ehrenberg. Flora, 1836, vol. ii. p. 491 -494. 



3 D 2 



