84 SUMMARY OF CURRENT RESEARCHES RELATING TO 



to vessels. Through this connection there is an active interchange 

 of formative material between the annual rings, which plays the greatest 

 part when, as in spring, the medullary rays cannot serve this purpose in 

 consequence of the accumulation of reserve-material. With regard to 

 the cells of the wood-parenchyme, it must be assumed that they serve, as 

 a rule, only for conduction in the tangential, and only exceptionally in 

 the radial direction. 



Order of Appearance of the first Vessels in the Leaves of Humulus 

 Lupnlus and H. japonicus.* — M. A. Trecul states that the leaves of 

 Humulus Lupulus and H. japonicus are palmatisect, with a stipule on 

 either side. In H. japonicus the stipules arise before the lower leaves, 

 and in some cases even before the upper ones ; and in the case of the hop 

 the leaves appear in the form of a little eminence only when the stipular 

 lamellae are already bilobed. The first vessel appears in the median vein 

 of the stipules before that in the median vein of the corresponding 

 leaf. The author then describes in detail the appearance of the vessels 

 first in the stipules and then in the leaves. 



Primary Liber-fibres in the Eoot of Malvacese.t— M. P. Van 

 Tieghem finds fibres in the primary vascular bundles in the root of 

 many genera of Malvaceae, also in some of Sterculiaceee and Tiliacese. 

 They have at present been met with almost solely in Leguminosae 

 among Dicotyledons, and are unknown in Monocotyledons or Vascular 

 Cryptogams. 



Development of Cork-wings on certain Trees.J— Miss E. L. Gregory 

 applies the term cork-wing to ridges of corky substance extending 

 lengthwise along the young stems of certain trees and shrubs. The 

 species examined may be considered as represented by three types : 

 viz. Quercus macrocarpa, Liquidambar styraciflua, and Euonymus alata. 

 The last genus is extremely interesting from a systematic standpoint. 

 No two species agree in the manner of cork development, while a 

 variety differs from its typical form only by a slight and unimportant 

 variation. The author describes in detail the anatomy of the superficial 

 periderm of Quercus microcarpa. 



Two kinds of Acer were further examined, one, A. campestre, con- 

 spicuously winged till the stem is three or four years old ; the other, 

 A. monspessulanum, much less so. The development difiers in both 

 cases from that of Quercus. Instead of five, as in Quercus, there are six 

 longitudinal bands growing faster than the remaining six ; this con- 

 tinues till a furrow is formed along the top of each wing, making a shell- 

 shaped appearance on cross section. In Liquidambar styracijiua the 

 cork-wings have one striking peculiarity which renders them an 

 exception to all other cases examined — this is their eccentric or one- 

 sided origin and growth. In this respect this species seems to stand 

 quite alone. The wings of the lateral branches appear always on the 

 upper side, and generally stand at such an angle as to form troughs 

 along the entire length of the branches. 



Mode of Union of the Stem and tlie Root in Angiosperms § — M. 

 P. K. Dangeard gives the following as his conclusions on this subject : 



* Comptes Eenduff, cvii. (1888; pp. 577-83. 

 t Ann. Soi. Nat. (Bot.), vii. (1888) p. 176. 

 X Bot. Gazette, xiii. (1888) pp. 249-58, 281-7. 

 § Comptes Eendus, cvii. (1888) pp. 635-7. 



