298 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the one class the tissues are sclerenchvmatous until growth is complete, 

 and then lignification ensues ; in the other class collenchyma forms 

 the only means of mechanical support until the flowering of the 

 terminal umljel, when sclerotization and subsequently lignification 

 ensues. Exceptions to these two classes are found in CEnanthe pim^jinel- 

 loides, where the peripheral system undergoes early lignification, and in 

 ■ some species of Heracleum and Daucus^ where the central cylinder like- 

 wise becomes lie-nified while still younsr. 



O t. o 



Reproductive. 



Embryology of the Angiosperms.* — 0. Yermoessen has studied 

 the ovule, embryo-sac, and fertilization of Neottia ovata, Orchis Jatifolia, 



0. maculata, Epijmctis 'pahisfris, and E. Jatifolia. The author finds that 

 all parts of the ovule, including the funicle, are derived from a single 

 subepidermal cell and are potential sporogenous tissue, but that by a 

 special process of sterilization, only a few special cells fulfil their original 

 function. The primitive archesporial layers are situated at the level of 

 the suture of two carpellary leaves and a sporangium is formed along 

 the ventral edge of each such leaf, Imt the sporangia of two neighbour- 

 ing leaves fuse ; ultimately certain portions of the sporangia become 

 isolated and give rise to the ovuliferous protuberances, while the other 

 portions remain sterile. The embryo-sac mother-cell develops at the 

 expense of the terminal subepidermal cell of the ovuliferous filament ; 

 no cap-cells are formed, but after two mitoses an incomplete tetrad 

 appears ; the internal cell develops into the embryo-sac, and the 

 remaining cells, which are speedily reabsorbed, are comparable to the 

 polar globules of animal-cells and. may be termed polar cells or polo- 

 cytes. The subsequent embryology is quite normal and the author 

 believes that the supposed abnormalities in Gypripedium may prove to 

 be simply slight variations of the process of development as seen in the 

 present types. Fertilization is brought about in a normal manner. 



CRYPTOGAMS. 



Pteridophyta. 

 (By A. Gepp, M.A., F.L.S.) 



Protocorm of Ophiog'lossoin.t — L. C. Petry gives an account of 

 the structure of a protocorm of Ophiof/Iossum vidgatum from Southern 

 Mexico, a brief notice of which was given by AV. J. G. Land in 1911. 



1. The protocorm is round with an apical pit which extends down 4/5 

 of the diameter of the protocorm, and at its bottom contains the apical 

 cell. 2. The leaf-V)ases are attached to the sides of this pit, with the 

 oldest at the top. The functioning leaf is the seventh. 3. The vascular 

 cylinder is an everted ectophloic siphonostele with endarch xylem. The 

 leaf trace consists of two strands attached separately to the cylinder. 

 The roots are numerous and outside the cylinder. 4. The apical cell is 

 a triangular pyramid, with segments dividing twice longitudinally l^ef ore 



* La CeUule, xxvii. 1 (1912) pp. 115-62 (2 pis.). 

 t Bot. Gaz., Iv. (1913) pp. 155-66 (figs.). 



