178 On the Anatomy of Vegetables. 



weakeft part of the membranous tiflue. If lacunae occur 

 more frequently in the monocotyledons, it is becaufe thefe 

 vegetables in general have lefs vigour, and an organization 

 lefs pcrfeft; or, if I may venture to fay, lefs vegetative power. 

 A phaenornenon which deferves the attention of phyfiologifts 

 is, that thefe lacerations inftead of hurting the vegetable 

 ferve only to increafe its ftrength by concentrating ir more. 

 Plants the texture of which is flaccid, and thofe in particular 

 immerfed in water, receive juices in abundance; but they 

 cannot alTimilate them, becaufe the organs are not fufficiently 

 vigorous in proportion to the volume of thefe plants, which 

 have more fize than real ftrength. But if by internal rup- 

 ture the organs which have become ufelefs are deftroyed and 

 the ufeful organs are retained; in a word, if one part of the 

 organization is facrificed to the other, the part which main- 

 tains itfelf receiving the whole nutritive fubftance will acquire 

 more ftrength, and the vegetable may ftill grow with new 

 vigour; for its ftrength will not be diminifhed, and its im- 

 pediments will be lefs. 



No lacunae are obferved in the embryo, becaufe its lacera- 

 tions are a real diforganization, which cannot take place in 

 beings that begin to live. They are formed therefore only 

 in the courfe of time. They (how themfelves in the petioles 

 of fern, in the ftems of the potamogetons, and in a multitude 

 of other vegetables like longitudinal tubes interfperfed through- 

 out the cellular tifliic. In the equifeta they affect a difpofi- 

 tion exceedingly regular; one greater than the reft forms a 

 tube in the centre of the ftem ; around this tube there arc 

 other very fmall lacunae arranged circularly, and fome larger 

 and cloler to the circumference are difpofed in alternate order 

 with them. The lacunae, of the leaves of the monocotyledons 

 are interfered by frequent partitions, which are only the cel- 

 lular tillne collected at certain diftances, and which clofes the 

 tubes bv membranous diaphragms. This organization, or 

 rather diforganization, appears through the tranfparent tiflue 

 of the typha, and a multitude of other monocotyledons with 

 fword-formed leaves. The fame phenomenon may be ob- 

 ferved in the tiflue of the (heaths of which the ftem of the 

 banana-tree is com poled. 



The rcjfio has longitudinal lacunae, and alfo tranfverfal 

 apertures in the thicknefs of the bark : it does not appear 

 that the latter kind of lacuna occurs often in vegetables. 



One might fufpecl that the large tubes of plants always 



begin by being lacunae, and that the internal vacuities, 



where a new tiflue, which increafes both the volume and 



dehfity of the vegetable, is developed, are only lacunas alfo. 



• Chap. 



