395 



Cf)£ ErcxZuvt) 0f 23otan». 



[desm 



grooved or striate as in Biatomacece. Be- 

 sides the increase of the species by means 

 of cell division and spores, minute zoo- 

 spores with lash-like appendages have been 

 discovered in Pediastrum, a genus which 

 belongs to a small group in which the 

 cells remain united so as to form a little 

 flat frond. In Closterium there is, more- 

 over, an organ at the extremity of the 

 frond consisting of a cell inclosing active 

 molecules. This is probably the male ap- 

 paratus. The armed spores are sometimes 

 found in a fossil state enclosed in flints 

 and other transparent minerals. Like Dia- 

 tomacece, Ehrenberg has attempted to re^ 

 fer them to the animal kingdom, but all 

 good authorities seem now convinced that 

 the proper place is amongst the Algce. Mr. 

 Ralfs' beautiful work on Desmidiacece may j 

 be consulted by those who wish for fuller 

 details. It does not appear that any indi- 

 vidual of the order can be applied to any 

 economical purpose. [M. J. B.] 



DESMIOSPERMEJE. One of the main 

 divisions of rose-spored Algce, in which 

 the spores are not scattered or simple, I 

 but form distinct chains like little neck- 

 laces. These are attached to a placenta, 

 which may either spring from the walls or j 

 their base, or may be strictly central. Far i 

 the larger portion of the more compound 

 species belong to this section. [II. J. B.] I 



DESMOBRYA. A term proposed to de- 

 signate that group of ferns in which the 

 fronds are produced terminally, that is, 

 from the apex of the caudex, and are ad- 

 herent to it : see Eremobrya. [T. M.] | 



DESMOCLADUS. 



lar rotatory motion of the leaflets of this 

 plant renders it an object of great interest. 

 In the trembling poplar, the leaf-stalk is 

 so constructed that the least breath of 

 wind causes the leaf to whirl ; in the sensi- 

 tive plant when the leaves are touched, 



Desmodium gyrans. 



they are perceptibly affected ; but in this 

 the motion in the leaves goes on if the 

 air be quite still, and they are scarcely 

 influenced by mechanical irritation. The 

 leaflets move in nearly all conceivable 

 ways, but do not fold on themselves ; two 



An Australian genus I of them may be at rest and the other re 

 of Restiacece, a sedge-like plant, with the I volying, or all three may be moving to 



branches of the stem rigid, the barren 

 ones awl-shaped, the flowering ones with a 

 single ovate few-flowered spike. [J. T. S.] 



DESMODITJM. An extensive genus of 

 herbs, shrubs, or small trees, of the pea 

 family, found more or less in all extra- 

 European countries, but chiefly confined to 

 the tropics. They are easily recognised 

 by the form of their pods, which are flat, 



g, or all three 



gether. Sometimes one leaf or two on the 

 plant only are affected, and at others the 

 movement is nearly simultaneous in all 

 the leaves. More commonly the lateral 

 leaflets are seen to move up or down, 

 either steadily or by jerks. The move- 

 i ments are most evident if the plant be in a 

 ! close hothouse with a strong sun shining. 

 It is said that by arresting the A T ital action 

 [ going on in the leaflets, by giving them 



straight or curved, with two or many , coating of gum, and thus preventing 

 joints, each jointed portion enclosing one ! transpiration and respiration, the move- 

 seed; in form, size, and thickness, they are men ts are stopped, but that they re- 

 much like the blade of a pen-knife, but commence when the gum is removed by 

 Iways notched, and wa ter. Upwards of 100 species are known, 

 3 a great proportion natives of South Ame- 



occasionally the upper also. The leaves 



[A. A. B.] 



are commonly made up of three leaflets, i ri ca an a India 

 but sometimes they are simple and lance- 1 



shaped or linear. The flowers are white, I DESMONCUS. A genus of palms in- 

 pink, purple, or blue, and usually disposed : habiting the forests of tropical America. 

 in terminal or leaf-opposed racemes or They have long slender flexible stems, and 

 panicles ; they have a bell-shaped four or ( pinnate leaves with the leaf-stalks pro- 

 five-toothed calyx, five narrow petals, and longed into whip-like tails, resembling in 

 ten stamens, all inserted into a tube or one ' general appearance the calami of the East- 

 of them free. The most interesting, al- ern Hemisphere, and like them also, they 

 though by no means the most beautiful, climb over and amongst the branches of 

 plant in the genus is D. gyrans, the Moving j trees, and support themselves by means of 

 plant, a native of India, and often found in the hooked or recurved spines attached to 

 cultivation in plant stoves ; its leaves are ! all parts of their leaf -stalks. The flower 

 made up of three oblong or lance-shaped . spikes are simply branched, and have male 

 smooth leaflets, the two lateral ones much flowers upon the upper, and females upon 

 the smallest. The flowers are violet, and the lower part of the branches. The males 

 arranged in terminal racemes. The singu- 1 have a thin three-cornered calyx, a corolla 



