Meyen's Report for 1839 on Physiological Botany. 17'> 



the blossom comes out through one of the openings (the up- 

 per one), as in Ajwuogeton distachys, etc., or as hi Sjjargunium 

 ramosum, Commelina tubcrosa, etc., ^vhere no trace of it is seen. 

 In most cases the sides of the cleft are connected the whole 

 length, and the cleft appears then as a line, Avhich is cither 

 straight or curved ; a transverse section then shows the posi- 

 tion of the edges of the cleft. All these cases are fully ex- 

 plained by a series of beautiful delineations. The little bud 

 appears in the form of a small wart at the bottom of a circular, 

 oval or lozenge-shaped frame (Einfassung) ; in Amaryllis carnea 

 the edges of the cleft are open only above, and the rest of 

 their length they are grown together. The cleft appears ho- 

 rizontal ( Veratrum), and when the edges become lengthened 

 it acquires the appearance of a divided or even of a simple 

 ligula, according as the inner edges are more or less perfectly 

 connated. In Rajania hastata and Tamus communis the inner 

 edges remain free. Finally, says M. de Jussieu, the destruc- 

 tion of the continuity in the cotyledon end of the embiyo can 

 sink to a mere point, as is very frequently the case in the 

 Gramineas and Cyperaceae, or this point may entirely escape 

 observation ; however, all these modifications are only different 

 degi'ees of the same organization. As one may draw a con- 

 clusion concerning the position of the bud from the position 

 of the cleft, one soon observes the relation existing between 

 the cotyledon and the radicle end ; the former is often much 

 larger than the latter. 



5l. de Jussieu then proceeds to the examination of Lind- 

 ley's theory, according to which the monocotyledonous embryo 

 may be considered as a dicotyledonous, from which one cotv- 

 ledon has disappeared, and the other has wound itself round 

 the plumula and grown together at the edges. M. de Jussieu 

 brings forward a number of interesting observations in oppo- 

 sition to this theory, and arrives at the result that the mono- 

 cotyledonous embryo, as far as regards its cotyledon part, may 

 be perfectly compared to a bud. Finally, the variable forms 

 W"hich the monocotyledonous embryos assume are considered ; 

 and the author concludes, that the stem of some monocotyle- 

 donous embryos has a disproportionate excrescence on one 

 side, which has to a certain extent the appearance of a cotyle- 

 don, and performs its functions, particularly in such cases 

 where the true cotyledon is imperfect, and reduced to the state 

 of a mere case or sheath. It is to be expected, that this sub- 

 ject, treated of by M. de Jussieu, will shortly receive its perfect 

 solution ; it is however a gigantic work to examine the genesis 

 of all the above-mentioned monocotyledonous embryos, par- 

 ticularly as it appears that the formation of tlic cotyledon is 



