J- . 1 



SPECIES OF MESEMBRYANTHEMUM. 59 



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formula and allied sections. These plants constitute collectively a group that 

 is absolutely distinct from all other flovvering plants both in appearance and 

 manner of growth, for the way in which the new growth bursts through the 



skin of the old one more nearly resembles the changing of the skin among 

 insects than anything else I can liken it to. No other plants do this. As an 

 example of this curious mode of growth, I will illustrate it by describing 

 what takes place in M. disdtum, N. E. Br.^ and its allies. On PL 5. fig* I> is 

 represented a branch as it appears when the season's growth is completed in 

 late spring. It is seen to terminate in a fleshy cone bearing two short leaves 

 at its apex, and is supported upon a long internodc of stem arising from a 

 pair of longer leaves with a smaller cone in each axil. At this period the 

 cone and leaves are green and remain so for a time, then the two long 



spreading leaves and the short ones at the tip of the cone wither and dry np, 

 and the green skin of the cone gradually assumes a greyish or pale brownish 

 colour, and tlie plant then i)resents a somewhat dead or dying appearance, 

 its leaves being dried up. In late autumn each cone bursts, revealing a 

 fresh pair of long spreading leaves, free to their base, where they are con- 

 nate around the stem, and bearing u[)on them the fragmentary remains of 



the ruptured dried-up skin of the old cone. A few days afterwards there 

 emerges from between them at their base the early stage of a new cone-like 

 growth as I have represented on PL 6. tig. 11. At first tlio yonng cone is 

 cylindric and almost indistinguishable from the internode below it, as is 

 shown in this fignre ; afterwards it enlarges and assumes its characteristic 

 cone-like form. The cone is really formed by a pair of leaves being united 

 for the greater part of tlieir length into an apparently solid mass, the tips 



only being free and spreading. In tjie centre of the base of the cone a bud 

 forms tliat gradually develops a pair of leaves tliat are not united, but have 

 their upper surfaces closely applied to one another. They gradually enlarge 

 within the cone at the expense of the nutriment contained in the latter, so 



that as the nourishment is gradually absorbe<l the substance of the cone is 

 gradually being replaced by the n©w pair of free leaves, which ultimately 

 completely fill the skin of the old cone without materially altering its shape, 

 although in autmnn they may greatly increase its size. These changes go 

 on unseen (and, until studied, unsuspected; within the interior of each cone, 

 and until the old dry skin is burst there is no visible evidence t^at anything 

 of the kind has taken place, any more than there is evidence that a cater- 

 pillar Is gradually developing a new skin inside the one that is visible. 



■ The flowers also offer some points of interest, such as their response to 

 light, susceptibility to temperature, and daily increase in size after their tirst 

 expansion. With reference to their fertilization, so far as I have observed 

 in tlie Sphasroid group, many or possibly most of the species seem infertile to 

 their own pollen, and yet when I have examined the stigmas oE various 

 species under a microscope I have always found them to be plentifully 



