M. Ch. Naudiu on Hyhridity in Plants. 239 



Datura Metel and Meteloides are at least as nearly allied 

 to one another as the two preceding ; but, from the second 

 generation, their hybrids cease to resemble them, and a 

 certain number of individuals return to one or other of the 

 two parent forms. Let us therefore conclude that these 

 forms are specific, that they each have their autonomy and 

 deserve, notwithstanding their affinity, to be distinguished 

 from one another. 



Nicotiana macrophylla and N. angustifolia combined in the 

 " Prodromus" of De Candolle with N. Tahacum, give hybrids 

 which, after the second generation, manifest a very appreci- 

 able commencement of return towards the producing forms. 

 These last have therefore also their manner of growth pro- 

 per to each of them. Why do we not admit them as dis- 

 tinct in our botanical catalogues ? 



But when the forms are so closely allied to one another 

 that they are with difficulty disthiguished, their hybrids 

 must differ still less from one another than they differ be- 

 tween themselves. The data furnished by hybridisation, 

 therefore, here lose their value ; but then it becomes a mat- 

 ter of indifference, whether to separate the two forms as 

 distinct species, or to combine them, by the title of simple 

 varieties, under a common specific denomination. 



It follows from all we have said, that the application of 

 the terms hybrid and cross is determined by the rank which 

 may be assigned to the individuals from the crossing of 

 which the mixed forms requiring to be named have been 

 produced — that is to say, it is entirely left to the judgment 

 and tact of the nomenclator. 



On Diplostemonous Flowers ; loiili some Bemarhs upon the 

 Position of the Carpels in the Malvacece, By Alexander 

 Dickson, M.D., Edin. (Plate III.)* 



It has long been known that in Geranium and its allies, 

 the stamens superposed to the petals are external to those 

 superposed to the sepals. That this is the case is very dis- 

 tinctly seen in the adult state, where the* dilated bases of 

 the filaments of the outer stamens overlap those of the inner. 



* Read before the Botanical Society of Edinburgh, Feb. 11, 1864. 



