PREFACE. XXI 



originally arose from the feeling of the intimate relation- 

 ship between external nature and human nature, it is 

 also its aim to grasp and bring to perception, the fur- 

 thest depths of this connection. 



Partly during the printing of these pages, partly after 

 its conclusion, I met with various literary novelties, of 

 which I could have wished to have availed myself in 

 passages on which they bore, in particular, Mettenius's 

 ' Beitrage zur JBotanik' (Heidelberg, 1.850), in which 

 occurs an exact description of the discovery of spermato- 

 zoids in Isoetes, mentioned cursorily at page 144 from 

 information derived from a letter from the author.* 

 Gsertner's important work, on the Production of hybrids in 

 the Vegetable Kingdom, {Die Bastardzeugung im Pflan- 

 zenreich, Stuttgart, 1849), first reached me after my ob- 

 servations on Cytisus Adami, p. 316, were printed. There 

 is no absolute decision there even, whether this remarkable 

 intermediate species is a hybrid, produced by fertilisation 

 from Cyt. Laburnum, and C.purpureus, or not; on the 

 other hand various notices on the same subject had been 

 published, which I had overlooked, especially the informa- 

 tion of Schnittspahn's paper, in the third Year's publication 

 of the Horticultural Society of the Grand-duchy of Hesse, 

 {Mitth. des Gartenvereins im Grossherz. i/ei's., Darmstadt, 

 1842, p. 38,) that Adam obtained his plant, by budding 

 C. purpureus upon C. alpinus.f During the first year 

 the grafted buds remained undeveloped, but many ine- 

 qualities of the surface displayed themselves around 



* Tliese points are further referred to in editorial notes. — A. H. 



t This probably means C. alpinus, Lamk., the same as C. laburnum, L., 

 and not C. alpitms, Mill., for the C. Adami of gardens returns on all hands 

 into G. Laburnum, L., and not into C. alpinus, Mill. 



