622 SUMMARY OF CURRENT RESEARCHES RELATING TO 



given species, and affords distinctive specific characters. The laticiferous 

 elements occur in the different tribes of the family. 



Kuster, E. — Beobachtungen iiber Regenerationserscheinungen an Pflanzen. 

 (Observations on regeneration in plants.) 



Beih. z. Bot. CentraM. Orig. Arbeit, XIV. (1903) pp. 316-26 (6 figs, in text). 



Reproductive. 



Lagenostoma Lomaxi, the Seed of Lyginodendron.* — F. W. Oliver 

 and D. H. Scott give an account of the structure of this seed which 

 occurs in calcareous nodules of the lower Coal-measures. It approaches 

 the Gymnosperm type in that the integument and nucellus are distinct 

 in the apical region only, the body of the seed which contains the large 

 single macrospore with traces of prothallial tissue, showing complete 

 fusion of integumental and nucellar tissues. The seed is remarkable 

 in having a large nucellar pollen-chamber, around which the free part 

 of the integument forms a complicated envelope composed of radiating 

 chambers, usually nine in number. A single vascular bundle enters at 

 the chalaza, and branches below the macrospore into nine radially 

 running bundles, each of which passes to the apex of the seed. When 

 young, and sometimes also at maturity, the seed is enclosed in a cupule, 

 extending in young specimens, above the micropyle. The pedicel and 

 cupule bear numerous capitate glands which closely agree with the 

 glands on the vegetative organs of Lyginodendron Olilhamium. The 

 structure of the vascular bundle in the pedicel strengthens the con- 

 clusion that the seed belongs to Lyginodendron. The evidence thus 

 indicates that in a transitional type, such as L. Oldhamium, with leaves 

 wholly fern-like in structure and form, but with decided Cycadean as 

 well as Filicinean characters in the anatomy of stem and root, the seed 

 habit had been as fully attained as in any known palaeozoic Gymnosperm. 

 Probably many other of the plants grouped under Cycadofilices also 

 possessed seeds. 



Development and Structure of the Seed-Coat in Gentianaceae.f — 

 J. Guerin gives the results of his investigation of 30 genera, including 

 204 species of this order. With the exception of the saprophytic Vogria, 

 and of Obolaria virginica, the ovules of which are naked, the ovule of 

 Gentianacege has always a single integument. The number of layers 

 which this comprises is very variable ; in the Menyanthoidere it reaches 

 16 to 20, while in the Gentianoideas there are fewer, 10, 8, 6, or in 

 some species of Gentiana only 2 or 3. In the Gentianoideae the inner- 

 most layer shows no peculiarity, in the other tribe it is early characterised 

 by the radial division and elongation of its cells. In the Gentianoidea? 

 there is no vascular bundle in the integument, in the Menyanthoidea? 

 the vascular bundle is well developed. The embryo-sac which by 

 absorption of the nucellus is in contact with the integument, is generally 

 very small, but in some Gentians it becomes very large, and the anti- 

 podal cells are well developed and often numerous. 



The course of development of the seed-coat is different in the two tribes. 



* Proc. Roy. Soc, lxxi. (1903) pp. 477-81. 

 t Comptes Rendus, cxxxvi. (1903) pp. 1094-7. 



