ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 825 



through all the cells of the parenchymatous tissue ; (2) Latex-tubes 

 segmented, and the segments of equal length ; (3) Latex-tubes seg- 

 mented, with the segments of unequal length ; and (4) Latex tubes 

 unsegmented ; in the true EuphorbiefB. 



Anatomical Structure and Development of Ceratophyllum.* — 

 This is described in detail by Herr J. E. F. af Klercker, the point of 

 chief interest determined being that the dermatogen always divides 

 only by anticlinals, and, in young apices of stems, appears to possess 

 only a three or four-edged initial, in older apices apparently several. 

 As a rule the periblem and plerome have distinct initials, the latter in 

 young stages only one, in older stages several. In exceptional cases 

 a single group of initials gives birth to both periblem and plerome. 



Lenticels-t — Dr. A. Zahlbruckner has examined the structure of 

 the lenticels in leaves, with the view especially of determining the 

 question whether they are completely closed in winter. For this pur- 

 pose Stahl's apparatus was employed, and applied to the leaves of 

 Jasmins Eippocastanum and TJlmus effusa, and with the result of 

 showing that they are not completely closed, although their structure 

 in this respect may be different from what it is in summer. In Sam- 

 hucus, Gleditschia, and the lilac, the lenticels did not permit a greater 

 quantity of air to pass through them when they had just emerged 

 from the bud than in winter. Owing to the power of swelling of the 

 substance which fills up the cells of the lenticels, they allow less 

 water to pass through them when saturated with water than when dry. 

 The author was able to establish fully the connection between the 

 lenticels and the air-passages, not only of the bark, but of the wood, 

 in consequence of which a complete circulation of air is kept up 

 through the plant In branches destitute of lenticels other means of 

 aeration are present. 



The special anatomical construction is described of the lenticels 

 of lihus Coriaria and Euonymus verrucosus, the former belonging to 

 the type in which the cells are all densely filled with a corky sub- 

 stance ; the latter to the type in which, in addition to the cells filled 

 with corky substance, are others of a sclerenchymatous character 

 with lignified walls, perforated by simple pores which connect them 

 with the adjacent cells. 



Anatomy of the Wood of Conifers.J — Dr. P. Pfurtscheller describes 

 the ai)pcaraiice of certain tracheids in the wood of Ahies excelsa, Picea 

 vulgaris, Larix europaea, Ahies Douglasii, and other coniferous trees, 

 almost wanting in Abies pectinaia. This was a projection in the 

 mcnibrane in the form of a spiral thickening, erroneously described 

 by sornc observers as a striation, with which it has in fact nothing to 

 do. In some cases the author observed a striation on the same 

 trachcid, and satisfied himself that the two structures were entirely 

 unconnected with ono another. This tendency to the formation of a 



• SB. Bot. fiiillHk. Btrwkholm, May 12, 1884. See Bot. Centralbl., xxi. (1885) 

 p. Ifi?. 



t Vcrh. K. K. Zool.-Ikit. Gcacll. Wicn, xxxiv. (1885) pp. 107-lG. 

 : Ibifl., pp. 53.5-42 (2 pis.). 



