366 Linnean Society. [Jan. 16, 



stances of the intumescence of a stem produced by a ligature, and 

 the germination of an apparently budless stem, in support of his 

 views; between which and those of Dr. Allemao, Mr. Miers is con- 

 sequently unable to perceive any essential difference. 



Mr. Miers further quotes, from early works of Mirbel, the proof 

 that; as long ago as 1802 and 1809, he accurately depicted and de- 

 scribed the origin and formation of similar vessels in germinating 

 seeds of Nelumbo and of the Common Haricot ; and refers to plates by 

 him in the 5th and 13th volumes of the ' Annales du Museum,' 

 showing the ascending system of spiral vessels in the plumule and 

 cotyledons, and the descending system of dotted vessels in the 

 radicle. 



Dr. Allemao further states, that although the " bolbo radicular " is 

 always the chief growing point of the radicle, he observed, in Euphor- 

 Mace(S, four other cruciform branches, on the same horizontal plane, 

 proceeding from this radicle. The same fact was described more 

 than forty years ago by Auguste de St. Hilaire (Ann. du Mus. xix. 

 p. 467) in the germination of a Ranunculaceous plant {Ceratoce- 

 phalus). In this, besides the main shoot, growing in the same way 

 as an ordinary exorhizal root, five other branching rootlets are 

 shown to be produced on one plane, from the collar of the young 

 root, which make their appearance through lacerations of the ex- 

 ternal coat. Their earliest indication is in the form of tubercles, 

 through the investing covering of which these rootlets burst a pass- 

 age, in all respects similar to the coleorhiza in the germinating em- 

 bryos of Monocotyledonous plants. The coleorhiza is sometimes 

 extended to some distance along the rootlet, but in other cases it 

 forms merely a swelling round its base. The same appearance, 

 although far from general, was observed by St. Hilaire in the ger- 

 minating embryos of numerous other exorhizal plants, as Myosurus, 

 Plantago, Valerianella, Urtica, Senecio, Sonchus, Calendula, Matri- 

 caria, Veronica, Phaseolus, Medicago, &c. In Tropeeolum the radicle, 

 although exorhizal, exhibits a kind of valve-like opening for the exit 

 of the plumule, which has been called a coleorhiza : and a somewhat 

 similar appearance is said to occur in the germination of the seed of 

 Viscum album ; this, however, Mr. Miers apprehends can refer only 

 to the coleorhizal mode of bursting of the attenuated expansion of 

 the thin covering of the albumen which is spread over the growing 

 radicle. 



Dr. Allemao, Mr. Miers adds, here considers the radicle of the 

 embryo as forming part of the caulicle or stem, and the root as ori- 

 ginating in the subsequent growth of the embryo, after it is released 



