SELECTED NOTES FROM SOCIETY'S NOTE-BOOKS. 189 



Fig. 2. — at. at., antennae, consisting of 11 joints ; Ibr., labrum, or 

 upper lip. 

 j^ 3. — m.m., mandibles; the strong, prehensile outer jaws, Avhose 

 special design is to seize hold and roughly bruise food. 

 They not unfrequently, as in the present case, have a fringe 

 of hairs along the inner margin. 

 ^^ 4. — tnx. mx., maxillae, inner lesser jaws. The maxillpe, with 

 very few exceptions, have invariably palpi attached to them, 

 here marked mx.p. mx.p., maxillary palpi. The hatchet 

 shape of the terminal joints of the mx.p. is one of the 

 generic characters of the CoccineUa. 

 ,, 5. — mt., mentum, chin ; l, labium, lower lip ; Jp., labial palpi. 

 In making a model of the mouth the shaded portions only of 

 Figs. 2 — 5 should be coloured. 



Drawn by Mr. Tuffen West. 



Selectcb IRotee from tbe Socictij'6 



Potassic sulphate is an object virhich I have seldom seen except 

 in my own collection. The chemical formula for this salt is K^ 

 SO4, or more exactly SO. (KO^). It is remarkable for crystallising 

 in two distinct forms. One cannot fail to observe the multitudi- 

 nous shapes the crystals have assumed here. F. J. Allen. 



Sections of Stems of Plants.— It is perhaps hardly necessary 

 to remind members of the P.M.S., that the stems of both 

 Exogens and Endogens are made up partly of cellular tissue and 

 partly of bundles of vessels and woody fibres, the difference 

 between them being that in the former the fibro-vascular bundles 

 form woody wedges arranged in concentric zones, and increasing 

 by additions to the outside ; whereas in Endogens the bundles 

 are scattered throughout the stem, those newly formed being in 

 the interior of the stem and curving outwards below towards the 

 circumference, where the bundles are in consequence more 

 crowded. Exogenous stems have a distinct pith and bark ; 

 Endogenous stems have not. 



In Euphorbia a?nygdaloides the wedges of woody tissue are 

 very small in proportion. In herbaceous Exogens, as the dahlia, 

 it frequently happens that the exterior of the stem grows so fast 

 that the pith-cells in the centre cannot keep pace with it ; hence, 

 an empty space is left, and we have a hollow stem, in most cases, 

 however, solid at the nodes or points where the leaves are jointed 

 on to it. The same thing sometimes happens in Endogens, parti- 

 cularly among the grasses, which have almost invariably a hollow 



Journal of Microscopy and Natural Science. r 



New Series, Vol. IL i88q. 



