ANNOTATIONS AND ADDITIONS. 51 



a state of vitality which was never entirely extinct, and 

 which is fanned into a fresh flame, or excited anew, by the 

 appropriate stimulus. Physiological phenomena can only 

 be comprehended by being traced throughout the entire 

 series of analogous modifications. 



( 4 ) p. 5. " Winged insects!' 



Formerly the fertilization of flowers in which the sexes 

 are separated was ascribed principally to the action of the 

 wind : it has been shown by Kolreuter, and with great in- 

 genuity by Sprengel, that bees, wasps, and a host of smaller 

 winged insects, are the chief agents. I say the chief agents, 

 because to assert that no fertilization is possible without the 

 intervention of these little animals appears to me not to be 

 in conformity with nature, as indeed has been shown in 

 detail by Willdenow. (Grundriss der Krauterkunde, 4te 

 Aufl., Berl. 1805, S. 405-412.) On the other hand, 

 Dichogamy, coloured spots- or marks indicating honey- 

 vessels (maculae indicantes), and fertilization by insects, are, 

 m much the greater number of cases, inseparably associated. 

 (Compare Auguste de St. Hilaire, Lecous de Botanique, 

 1840, p. 565-571.) 



The statement which has been often repeated since 

 Spallanzani, that the dioecious common hemp (Cannabis 

 sativa) yields perfect seeds without the neighbourhood of 

 pollen-bearing vessels, has been refuted by later experiments. 

 When seeds have been obtained, anthers in a rudimentary 

 state, capable of furnishing some grains of fertilizing dust, 

 have been discovered near the ovarium. Such hermaphro- 



