INTEODUCTION TO CRYPTOGAMIC BOTANY. 43 



the common carnation and sweetwilliam has given at once the 

 clue.* The ovules in this monster are replaced by carpels 

 more or less distinct to their base, and, in this condition, the 

 placentation is as truly marginal as in any Phsenogam ; and 

 whatever affinity there may be in the matter is prominent 

 only when the plant is reduced to its fundamental condition. 

 In other conditions the real relations of the parts are obscured. 

 Multitudes of similar cases might easily be brought forward in 

 confirmation of the law. It is to be considered, moreover, that 

 every observer differs, not only in the estimate of false affi- 

 nities, but in the amount of likeness from which they start. 

 Homologies, when once estabhshed, are certain, and must be 

 estimated by every competent authority at the same value. 

 Andrcea affords an excellent example. It is a moss in every- 

 thing except the dehiscence of the theca. There is an analogy 

 between this and the quadrifid capsule of Jungermannia, 

 but there the likeness begins and ends. The likeness is visible 

 only in the last stage of growth. If it were a case of affinity 

 it should be visible at once. There would have been a 

 development of elaters or something homologous within the 

 theca as in Jioiigermannia. 



80. It is desirable, again, before entering further on this 

 argument, to say a few words on the reproductive organs 

 of Cryptogams, at least on the female organs, for there is little 

 or no similarity between the male organs of Cryptogams and 

 Phfflnogams. There are no proper pollen globules, no ger- 

 minating of a cell to bring the walls in contact mth the embryo- 

 sac, nor is there any agreement between the mode of genera- 

 tion of the grumous matter or fovilla and the spermatozoids. 



In the more simple cases there is nothing at all analogous 

 to flower, but certain privileged cells are separated from the 

 threads or compact tissue of the matrix, whether naked, or 

 produced within a special tube or sac, and constitute the fruit. 

 These germinate almost exactly like pollen grains, and reproduce 

 the species. There are, sometimes, several kinds of spores upon 

 a plant, all capable of reproduction, though differing in appear- 

 ance. These spores, then, are homologues of the individual cells 

 * See Gard. Chron. 1850, p. 612 ; 1855, p. 280. 



