412 



SEXUAL DELATIONS OF PLANTS. Chap. & 



two sexual forms.* We have also seen that as 

 plants became affixed to the ground and were more 

 highly developed so as to be rendered phanerogamic, 

 they would be compelled to be anemophilous in 

 order to intercross. Therefore all plants which have 

 not since been greatly modified, would tend still to 

 be both diclinous and anemophilous; and we can 

 thus understand the connexion between these two 

 states, although they appear at first sight quite dis- 

 connected. If this view is correct, plants must have 

 been rendered hermaphrodites at a later though still 

 very early period, and entomophilous at a yet later 

 period, namely, after the development of winged insects. 

 So that the relationship between hermaphroditism and 

 fertilisation by means of insects is likewise to a certain 

 extent intelligible. 



Why the descendants of plants which were originally 

 dioecious, and which therefore profited by always inter- 

 crossing with another individual, should have been 

 converted into hermaphrodites, may perhaps be ex- 

 plained by the risk which they ran, especially as long as 

 they were anemophilous, of not being always fertilised, 

 and consequently of not leaving offspring. This latter 



* See the interesting discus- 

 tion on this whole subject by O. 

 Biitschli in his ' Studien iiber die 

 ersten Entwickelungsvorgange der 

 Eizelle,' &c. 1876, pp. 207-219. 

 Also, Dr. A. Dodel, " Die Kraus- 

 haar-Alge," ' Pringsheims Jahrb. 

 f. wiss. Bot.' B. x. Also, En- 

 frelmann, "Ueber Entwickelung 

 von Infusorien," ' Morphol. Jahr- 

 buch,' B. i. p. 573. An abstract 

 of this important memoir has 

 appeared in ' Archives de Zoolog. 

 expe'rimentide,' Tom. v. 1876, p. 

 xxxiii. Engelmann concludes 

 that the conjugation of various 



Infusoria, whether permanent or 

 temporary (in this latter case 

 called by him copulation) does not 

 lead to the development of true 

 ova, bit to the reorganisation or 

 rejuvenescence of the individual. 

 There seems to be a close analogy 

 in such a result with that which 

 follows from the union of the 

 male and female elements of dis- 

 tinct plants, for the seedlings thus 

 raised may be said to show re- 

 generation or rejuvenescence in 

 their greatly increased constitu- 

 tional vigour 



