498 
Anatomie. — Morphologie, Befruchtung, etc. 
White, H., On polystely in roots of Ovchidaceae. (Univ. ot 
Toronto Studies, Biological series, N°. 6. p. 1—20. pls, 1, 2. 1907.) 
Two or more steles are found in the roots of certain orchids 
belonging to the group Ophrydinae. In lateral roots this condition 
arises 1) as in Habenaria orbiculata by bifurcation of an originally 
monostelic central cylinder, or 2) as in H. blephariglottis by the 
appearance of a pith in a solid Stele, followed by the opening of 
the Stele forming a horse-shoe shaped mass from the free ends of 
which small steles are pinched off, or 3) as in H. hyperborea by 
several steles arising separately from the stem. The last mode is 
found also in the tubers, and it was this appearance which led Van 
Tieghem to adopt the view that several roots had fused. ln all 
cases the separate steles merge into a common plerome cylinder 
at the root tip, which condition elfectivefy disposes of Hanstein’s 
theory of the correspondence of plerome and periblem to central 
cylinder and cortex respectively. This research also lends strong 
support to the view that the pith is of extrastelar origin. 
M. A. Chysler. 
Cook. M. T., The embryology of Rhitydiphyllum. (Bull. Torrey 
Bot. Club. XXXIV. p. 179—184. pl. 10. 1907.) 
A study of this Cuban representative of Gesneriaceae shows 
that the embryosac develops normally from an archesporial cell 
which usually becomes the functional megaspore without dividing. 
The embryo is of the Capsella type, with slight variations, and the 
endosperm is cellular. Both endosperm and nucellus are used up 
during the growth of the embryo. M. A. Chrysler. 
Cook, M. T., The embryology of Rhisophora mangle. (Bull. 
Torrey Bot. Club XXXIV. p. 271-277. pl. 21, 22. 1907.) 
The habit of vivipary in the mangroves is found to be connec¬ 
ted with the following featüres in the development of the embryo: 
as the embryo sac matures the nucellus disorganizes, soon followed 
by the inner integument of the ovule. This is accompanied by the 
formation of an enormous amount of endosperm. Next occurs a 
considerable growth of the cotyledons, resulting in the forcing of 
the endosperm and one-third of the embryo from the embrj^o sac. 
Then' follows extension of the hypocotyl and modification of the 
cotyledons for the purpose of absorption. Finally the cotyledons 
elongate, and the embryo divides, allowing the hypocotyl and plu- 
mule to fall from the ovary. M. A. Chysler, 
Heidenhain, M., Plasma und Zelle. Erste Abteilung. Allge¬ 
meine Anatomie der lebendigen Masse. 1. Lieferung: Die 
Grundlagen der mikroskopischen Anatomie, die Kerne, 
die Centren und die Granulalehre. (Jena, Gustav Fischer. 
506 pp. 276 Textfig. 1907.) 
Das vorliegende Buch ist in erster Linie für den Anatomen 
bestimmt, und Verf. geht in seiner Darstellung daher überall in 
erster Linie von dem Boden der Erkenntnisse aus, die aus dem Stu¬ 
dium der tierischen, speciell der Vertebraten-Anatomie, gewonnen 
wurden. Die „Hilfswissenschaft” der Botanik wurde nur soweit her- 
