384* Prof. Meyen's Report of the Progress of 



comparison of them with the formation of the thallus in the 

 lower plants. " We have seen," says he, p. 38, t* according to 

 what has been said, in the organs of vegetation a constant pro- 

 gression from the symmetrical to the concentric formation ; not 

 however a fixed progression, but one interrupted by fluctuations. 

 The pure symmetrical formation in the lower order of plants 

 raised itself to the concentric on the stems of the Jungermannice 

 and Lycopodice ; this however did not yet appear openly, but 

 still showed a considerableaffinity tothesymmetricalformation. 

 In the Phanerogamia a weak tendency to the symmetrical for- 

 mation is yet often evident in the stem ; on the contrary, how- 

 ever, in general the most determined concentric organization 

 shows itself; while in the leaves the symmetrical formation 

 takes place in a manner not less remarkable than in the thal- 

 lus of the Cryptogamia. In the branches we often observed a 

 return to the symmetrical formation, while in the more highly 

 developed leaf-forms many phaenomena pointed to the ten- 

 dency of the petiole of the leaf to raise itself to a concentric 

 formation. We observed in the leaved stems and in the pin- 

 nate leaves the symmetry showing itself in a double form : 

 first, in a narrow circle, in the corresponding formation of both 

 side-halves of the individual leaflet; and secondly, in a wider 

 circle, in the symmetrical formation of the two opposite leaf- 

 lines sacrificing the symmetry of each individual leaflet." 



In flowers it rarely occurs that they are not separated by 

 a perpendicular section into two equal halves; and the general 

 rule is that all terminal flowers are regular ; that on the con- 

 trary irregular flowers are allotted to such inflorescences as 

 are not terminal. According to this the symmetrical formation 

 of the flowers stands in connection with their position. 



Fries* has endeavoured to solve the question, which vege- 

 tables might be regarded as the most perfect, in a very in- 

 genious manner. He first shows how the views of earlier 

 botanists on this subject were untenable; he refutes most ad- 

 mirably De Candolle's view, according to which the Ranun- 

 culacecB were the most perfect plants; for perfection in vege- 

 tables does not consist in the more perfect development of 

 any individual organ, but in the harmonious development of all 

 the organs collectively into a typical whole. Fries enumerates 

 the following among the criteria of the perfection of a vege- 

 table : 



1. The greater number of degrees of metamorphosis a 

 plant has to pass through, before the fruit is developed, the 



* Essay towards a new answer to the question : Which vegetables are 

 the most perfect? Transl. from the Swedish by Hornschuch. Flora, 

 1836, p. 1—16. 



