986 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Reticulations in Vessels.* — Dr. O. G. Petersen calls attention to tho 

 occasioual occurrence of a network with angular, or less often rounrlcd 

 meshes, and very delicate, almost colourless and transparent coil-walls, 

 clothing the cavity of individual cells. This occurs in Cordia Myxa, 

 Botujainvillea glabra, and Testudinnna eleplmntipes. It presents tho 

 appearance of an intermediate structure between trachea3 with bordered 

 pits and sieve-tubes. 



Secretory Canals of Araucaria.f — M. P. A . Dangeard finds Arau- 

 caria imhricaia to differ from all other Conifers at present observed in the 

 presence of secretory canals in the primary cortex of the root. While in 

 Pinus syh-estris each cotyledon receives only one fibrovascular bundle, 

 in Araucaria imbricnta seven or eight pass into the cotyledons, accompanied 

 by the secretory canals of the pericycle. The number of cf)tylcd(>ns is 

 either two or three. The secretory canals of the stem are independent 

 of the two systems which may be detected in the embryo, the one lying 

 a few layers below the epidermis of tho cotyledons, the other more 

 towards tho interior. 



Super-endodermal Network of the Root of Leguminoseae and 

 Ericaceae.J — M. P. van Tieghem points out that many of the Conifera), 

 Rosacea), Caprifoliaccas, and Crucifera; have the super-endodermal layer 

 of their root provided with a sustaining network. The author has found 

 a similar network in the roots of certain Legiirainosea^, notably Cassia, 

 and in certain Ericaceae, more particularly Clcthni. 



Sub-epidermal Network of the Root of Geraniace8e.§ — IVEVI. P. 

 van Tieghem and Monal state that the root of Geranium (G. molle, 

 Bohertianum, pyromicinn, sanguincum, rotundifolium, striatum, carallianum, 

 &c.) has below the piliferous layer a layer of large cells, constituting 

 what is usually called the suberous layer or exodcrm. Each cell of this 

 layer has on its lateral and transverse face a band strongly thickened 

 towards the interior. This constitutes the sustaining network. Tho 

 same character is found in Pelargonium and in Erodium. In E, arahicum 

 and c/n'i/m the sub-epidermal network is often interrupted, and sometimes 

 but feebly developed. 



Supporting Network in the Cortex of the Root.|| — According to 

 M. P. van Tiegliem, a great number of Dicotyledons and Gymnosperms 

 develope a supporting network in the cortex of their root ; tliis has not 

 been observed up to the present time either in Monocotyledons or Cryp- 

 togams. It is formed by a layer of cells being strongly thickened on 

 their radial and transverse sejita. This network may be eitlier simple 

 or compound, and may occupy three different positions. Most frequently 

 it belongs to the last cortical layer but oiie, and is in contact with tho 

 endoderm. This may be observed in many Crucifera3, Eosaccse, Cai^ri- 

 foliacese, &c. Sometimes, on the contrary, it is the external cortical 

 layer, as in GeraniaccEe; while sometimes it may occupy a position 

 intermediate between the two iircceding, as in Pliiz' phora Mangle. In 

 fact it will be thus seen that the network may occupy almost any 

 position between the epidermis and the endoderm. 



* Bot. Centralbl., xxxv. (1888) pp. 27-8. 



t Bull. Soc. Linu. Normnndie, i., 1886-7 (1888) pp. 174-7. 



j Bull. Sec. Bot. France, xxxv. (18^8) p. 273. § Ibid., p. 274. 



II Ann. Set. Nat., vii. (1888) pp. 375-8. 



