ZOOLOGY AND BOTANT, MICKOSCOPY, ETC. 987 



Exoderm of the Root of Restiacese .*— M. P. van Tieghem states 

 tliat the cortex of the root of KestiaceaB includes, as usual, two zones, 

 the thick internal layer sui-rounding the central cylinder, and the ex- 

 ternal layer. It is in the external cortical zone that the peculiar 

 cortical character which is the subject of this paper resides. 



All the Restiacete have this common character, that the exoderm is 

 folded ; but either this endoderm constitutes by itself the external 

 cortical zone and is derived directly from the differentiation of the 

 initial layer of the zone (as in Elegia, &c.) ; or it is only the outer- 

 most layer of a more or less thickened and lignified mass produced by 

 the centrifugal tangential division of the initial layer, and derived by the 

 differentiation of the merismatic layer of this zone {as in Bestio, &c.). 



Periderm of Rosacese.l — M. H. Douliot states that it is well known 

 that in the Pomeee the periderm originates in the epidermis, while in 

 the Amygdaleas and Pruneee it originates in the first layer of the cortex 

 situated immediately beneath the epidermis ; in the Buhi this same 

 formation originates in the endoderm ; and finally, as in the case of 

 Spirsea opulifolia, it may originate in a layer of cells situated beneath 

 the endoderm. It is thus seen that the periderm may be formed in four 

 different places in the stem of Rosacese, but the last case of all, where 

 it originates beneath the endoderm, that is, in the pericycle, is by far 

 the most common, and examples are met with in the Spirfeese, Fragariefe, 

 PoteriesD, and Eoseee. The author concludes by describing in detail 

 the formation of the periderm in Alchemilla valgaris. 



Plants which form their Rootlets without a Pocket. J — MM. P. 

 van Tieghem and H. Douliot hare already shown that rootlets and 

 lateral roots are formed in the pericycle by two successive tangential 

 divisions. There are, however, certain secondary differences which are 

 of interest, and which vary in the different families, as, for example, 

 that the root or rootlet is sometimes naked, sometimes enveloped in an 

 endodermal " pocket." Among Dicotyledons the authors have observed 

 the formation of rootlets without a pocket in fifteen families : — Cruciferse, 

 Capparideas, Fumariacete, Papaveracese, Eesedaceas, Caryophyllacefe, 

 Portulacacese, Illecebracese, Crassulaceee, Chenopodiacese, Amaranthacese, 

 Baselleae, Aizoacese, Cactacese, and Begoniacete. In Monocotyledons the 

 absence of a pocket is very rare, and the only instance cited by the 

 authors is Pandanus. In Gymnosperms the Abietine^ are destitute of 

 a pocket, also Taxus, Podocarpus, and Sequoia. 



Observations on Pinguicula. § — M. P. A. Dangeard continues his 

 observations on Pinguicula. An endoderm exists in the stem of all the 

 species the author has examined, the cells of this layer being often rect- 

 angular. The bundle which passes into the leaf proceeds from two 

 different sympodia. These sympodia follow in the stem a course 

 analogous to that found in Primula spectaMlis or Androsace septentrioncdis ; 

 they, however, may be found arranged in two different ways. The 

 sympodia either form a normal annual ring, or they are the same as in 

 the lower part of the stem. From this anatomical point of view, then, 

 the genus Pinguicula can be divided into two sections, 



* Bull. Soc. Bot. France, xxxiv. (1888) pp. 448-50. + Ibid., pp. 425-7 



X Ibid., XXXV. pp. 278-81. § Ibid., xxxv. pp. 260-3, Cf. tliis Joiunal, ante, p. 74. 



