62 INTRODUCTION TO CEYPTOGAMIO BOTANY. 



shaped calyx to the monadelphous stamens, though the male 

 and female flowers are associated ; and an ovary with many 

 erect ovules. Ambrosinia makes yet another step. The spatha 

 is well developed, and whether or no we consider the ten twin 

 anthers,* as belonging to as many stamens, we have a spadix 

 in the dissepiment, with the single female flower on the one 

 side, and the male on the other. The position of the ovules, 

 however, which is totally different from that of Pistia, is a curi- 

 ous instance of anomaly. It is but a step from Amhrosvnia 

 to ordinary Arads, and thus the affinity of Lemna to Arum 

 is proved, an affinity which coidd scarcely have been made out 

 without the intervention of Pistia; and when one such affinity 

 of a degraded form is ascertained, there is a clue to other simi- 

 lar affinities. One of the most striking instances of difference 

 of habit, is that between Cactus and Ribes, an instance which 

 was famihar in the mouths of all, when the natural system first 

 began to replace the Linnsean in this country, and yet no affinity 

 is more sure ; and almost equally striking is that between 

 nettles and figs, to which Dorstenia gives the true key. On 

 the whole, then, it is plain that immense differences on the 

 one hand, should not at once determine against affinity, nor on 

 the other hand, should striking resemblances mislead us. We 

 must not judge by isolated facts, but, as far as we can, by the 

 whole history and morphosis of plants, otherwise we shall never 

 arrive at affinities ; and if this course be pursued, I know of 

 nothing which can confound a single Cryptogam with the lowest 

 Phffinogam, and much less with Phaenogams high in the scale, 

 like Conifers. 



50. It may be a very good answer to the question, what 

 Cryptogams approach nearest to Phsenogams, that Club-mosses 

 present the greatest similarity in habit and in fruit. But we 

 cannot ignore the fact, that Club-mosses bear spores like other 

 Cryptogams, which, apart from the plant, undergo a variety of 

 changes, in consequence of impregnation, at a distant period, 

 and at length produce a plant, which springs at once into a new 



* See Cesati Ueber die Gattung Ambrosinia, Linn. v. ix. p. 281, tab. v. 

 flfC. 8, 9. 



