256 PHYSIOLOGICAL BOTANY. 



the mechanical action of these, and the materials which 

 they bring with them, contributing to it, &c. But this 

 conversion has not been proved to occur ; in all proba- 

 bility it is entirely false, and the currents of a fluid may 

 become suddenly changed; in the germinating cotyledons 

 of the Monocotyledons, when emitting radicles, they pass 

 suddenly upwards into the stem, and downwards into the 

 root. But it is perhaps unfair to criticise the author from 

 an old memoir, as since that time he has proceeded with 

 his investigations, and we have still much to expect 

 from him. 



New Researches upon the Development of the Axis and 

 Appendages of Plants. By M. C. NATJDIN. Annal. d. 

 Scienc. naturell., 3 ser. vol. i, p. 162. These observa- 

 tions are in general accurate and valuable, although they 

 are not new. The leafy parts (appendages), says the 

 author, are the lateral products of an axis, which at first 

 consist of cells only ; they also at first consist of cells 

 only, not containing vessels, and the apex of the axis, the 

 centre of a bud, exhibits a tubercle (mammelon) which is 

 in connexion with the pith. The second part of my 

 Select Anatomico-botanical Plates contains many figures 

 which show this more distinctly than the author has done ; 

 but so it is, our labours run parallel with those of fo- 

 reigners, yet we are generally a little before them. But 

 no; the author is actually acquainted with Duchartre, Guil- 

 lard, and Schleiden, who have investigated this subject. 

 Recently, in the second part of my ' Anatomy of Plants/ 

 the plates contain further illustrations of this subject. 

 What he states of a few Monocotyledons only, viz. that 

 the spots, where the vessels arise, are denoted by a mo- 

 dification of the cellular tissue, applies to most plants, 

 and has also been illustrated in the part of my work 

 alluded to above. The distinction which the author 

 makes between the axis and the foliaceous parts, viz. 

 that the former grows at the extreme point, whilst no 

 addition takes place at the extremities of the latter, is 



