120 Anatomie. — Cytologie und Befruchtung. 



phloic tube oi vascular tissue with widely separated leaf-gaps. 

 Dictyostele, a tubulär network derived from a solenostele by 

 the overlapping of the leaf-gabs. Proto stele, a stele which is 

 supposed to be primitive in structure. Hy ste r ost ele, a stele 

 which is supposed to be reduced in structure. Meristele, a 

 vascular bündle in the old sense, but excluding actino- and 

 haplosteles. 



The author then gives a detailed account of the deve- 

 lopement of the vascular System of the seedling of Danaea 

 simplicifolia. At the very base it consists of a haplostele 

 which, however, does not pass through a medullated or a 

 solenostelic stage, but becomes converted into a dictyo- 

 stele by branching through the departure of the leaf- 

 traces. Subsequently a central Strand arises as a branch from 

 the inner surface of the dictyostele which traverses the central 

 ground-tissue obliquely upwards, and fuses at intervals with the 

 inner surface of the dictyostele at different points, generally 

 opposite the root insertions. Later on stil! this internal Strand 

 branches once or twice and the mature structure is finally 

 attained. No secondary thickening was found at any point in 

 the plant. 



The comparative anatomy of the order is then dealt with, 

 and the diagnostic value of the histological characters is dis- 

 cussed. The vascular arrangement in the petiole is described, 

 and Miss Shove's discovery of the centrifugal developement 

 of the phloem in the stem of Angiopterls is confirmed and 

 extended to the petioles of the Marattlaceae generally. 



In conclusion the author adversely criticises the use of the 



endodermis, pericycle, pith and the histogenetic layers as 



morphological criteria, and proposes to abandon the stelar 



theory altogether, and to Substitute for it a conception of 



vascular Strands and non-vascular tissue. 



D. J. Gwynne-Vaughan. 



Cannon, Wm. A., A Cytologie al basis for the Mendelian 

 laws. (Bulletin of the Torrey Botanical Club. Vol. XXIX. 

 1902. p. 657—661.) 

 The writer believes that the laws of Mendel, namely, the 

 law of dominance and that of the Splitting of the hybrid race, 

 are supported by recent cytological studies. The theory that 

 Variation in hybrids is, in some way, connected with the for- 

 mation of the sex cells is supported by Guy er 's work on 

 hybrid pigeons and that of Juel on Syringa. Prof. Cannon 

 has discovered similar conditions in his study of a fertile cotton 

 hybrid. Pure races of animals organize sex cells of pure 

 descent and it is suggested that fertile hybrids of both animals 

 and plants behave in a similar manner. This would imply that 

 two sorts of germ cells are formed in the ovary and two in 

 the anther. The füll paper with plates will be awaited with 

 interest. Charles J. Chamberlain (Chicago). 



