874 Dr. A. Braun on the Veyefahle Individual. 



Veronica officinalis, C/ianuedri/s, &c., Viola syhatica, Lysimachia 

 ihtjrsifolia, .l/i/ssuui sa.iali/e, and sonic other Cruciferce, Echeveria 

 coccinea, all the species of Mclilotus, Medicac/o, Galecja, in Pisum, 

 and many other legiiniinous plants, and in Succisa pratensis, 

 AnacijcJu,-<, Pi/rcthrnni, Pohjyunum, liistortn, &c. A familiar ex- 

 ample occurs in Secalc : its spicitcrous culm forms the shoot of 

 the first degree, the lateral spikelets which compose the spike 

 itself are those of the second*, and the florets in the axils of the 

 superior leaves (palca^) of these spikelets are the shoots of the 

 third degree, i. e. the third generation of the cycle. A quadri- 

 membral succession of shoots occurs in Trifolium inontnnvm, 

 Hedysarum coronarium, and in several of the New Holland phyl- 

 lodineous Acaci(P. Several sj)ecies of Carex, e. g. C maxima and 

 leptostachys, have a trimcnibral succession of shoots uj) to the 

 male flower and a five-mem bral one up to the female. 



If we were to reckon the similar generations which are reared 

 one above the other until the tree gains strength enough to per- 

 fect its flowers, in many trees without terminal buds, as in the 

 AVillow, or the Limef, we might find a number of generations 

 equal or even much superior to that presented by Aphis. 



Besides the generation essential \o itself, and by which it gives 

 existence to the next grade in the cycle, every generation may 

 have still another unessential reproduction, which only extends 

 the same grade. As above we distinguished between essential 

 and unessential shoots, so here accordingly we must distinguish 

 an essential succession of generations, — the true alternation of 

 generation, — and an unessential one. Very often both occur in 

 the same species of plants. A fine example of this is shown in 

 Lysimachia nummularia, from whose creeping and rooting leaf- 

 axis are emitted not only peduncles, but here and there a new 

 creeping leaf-axis exactly repeating the original one (except as to 

 the two early-lost cotyledons) : and from the undetermined leaf- 

 bearing main-axis of Tropceolwa minus are emitted in regular 

 alternation three lateral flowers at a time, and then again one 

 (unessential) leaf- shoot. In Cardamine amara the first genera- 

 tion (the stem bearing foliaceous and superior leaves) is repeated 

 in a twofold manner, by lateral branches from the cauline leaves, 

 and by creepers from axils of the root-leaves. Similar relations 

 obtain in Mentha and a large number of other plants. This 

 same phfcnomenon is repeated in the animal kingdom. The 

 polype-like nurses of the Medusa increase as such (according to 

 Sars and Von Siebold) by lateral buds and runners. Syncorynce 



* Secalc, in fact, has no terminal spicule ; neither has Triticum mono- 

 rocciim, while the other cultivated species of Triticum have. 



+ I have described the Grape in reference to this subject in another 

 place (Verjiingung, p. IT)) [Henfrey's Tranil. op. cit. p. 4fi]. 



