ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 81 



roots and buds on the root and lower part of the hypocotyl of Phan- 

 erogams in those cases where the structure of these organs is binary. 

 In all these cases, which are very common, the root, whether terminal or 

 lateral, primary, secondary, or of any other order, forms its subsidiary 

 roots in the peri cycle in front of the intervals which separate its two 

 xylem-bundles from its two liber-bundles, and places them in consequence 

 in four longitudinal rows. The author terms those rootlets " isostique " 

 when the mother-root has more than two, " diplostique " when it has 

 only two xylem-bundles. 'Whenever a root, whether primary, terminal, 

 or lateral, is binary, its branching is governed by the second of these 

 laws. The same law governs the arrangement of the normal buds which 

 frequently make their appearance on the hypocotyl. 



The local production of double roots and double buds is not un- 

 common, especially in Urnbelliferaa. The normal hypocotyledonary buds 

 above alluded to almost always spring from the pericycle of the root or 

 of the stem ; the only known exception is in the case of the Linariaceae, 

 where they are of exogenous origin. 



Epidermal Glands.* — M. P. Vuillemin has examined the structure 

 of the epidermal glands in the natural orders Plunibaginaceas, Frankeni- 

 aceas, and Tanmriscineas. In those of the two latter orders he finds a very 

 strong similarity to one another. Those of the Plumbaginaceae, while 

 resembling the glands of the other two orders in their structure, origin, 

 and functions, yet present some well-marked morphological differences. 

 They are, in all three orders, hairs transformed into organs of excretion, 

 and intended to complement the action of the stomata. They detain the 

 waste products arrested by the thick walls which bound the intercellular 

 spaces, but which are able to pass through the walls of these secreting 

 cells, which are always punctated, the gland opening outwards through a 

 very narrow orifice, and being always lined at its base with a layer of 

 protoplasm. 



In the Plumbaginaceae each gland always consists of eight secreting 

 cells. The substance secreted may be entirely volatilizable, or may be 

 mucilaginous, or may contain a large quantity of salts of lime in solution, 

 which is deposited, on evaporation, over the whole surface of the leaf. 

 In the Frankeniaceae and Tarnariscineas each gland consists of only two 

 secreting and two subsidiary glands. The secretion is, in the Frankeni- 

 aceas, generally calcareous, solidifying on evaporation ; while in the 

 Tamariscineae it is resinous, not yielding a calcareous concretion on 

 evaporation. 



Prickle-pores of Victoria regia.j — Mr. J. H. Blake, having examined 

 the large prickles on the leaf-veins and petioles of Victoria regia, finds 

 that only the larger ones are penetrated by a fibro vascular bundle, and 

 that the opening or ostiole described as existing at the apex of the spine 

 is not invariably present, and is probably the result of injury. 



Morphological Peculiarity of Cordyline australis.J — Prof. F. 0. 

 Bower records a peculiarity in this plant growing in Ceylon, that, when 

 the stem assumes an oblique or horizontal position, lateral shoots are 

 put out from the lower side of the main axis, which direct themselves 

 vertically downwards. They are of exogenous origin, with exceedingly 



* Ann. Sci. Nat.-Bot., v. (1887) pp. 152-77 (1 pi.). 



t Arm. of Bot., i. (1887) pp. 74-5. 



X Proc. Phil. Soc. Glasgow, xviii. (1887) pp. 317-9 (1 pi.). 



1888. a 



