332 SUMMARY OF CURRENT RESEARCHES RELATING TO 



pensor originates iu a group of cells at the proximal end of the embryo. 

 This same group of cells at a later stage forms the root-meristem. In 

 one instance branching of the embryo gave rise to two approximately 

 equal embryos. The rapid growth of two groups of apical meristematic 

 cells initiates the cotyledons. Lvsisjenous canals, containing both tannin 



mi 



and mucilage, arise before the foliage leaves are differentiated. The 

 fused cotyledons are very intimately connected. Morphologically the 

 suspensor is a root-cap. There is a close resemblance between the 

 embryology of Encephalartos and that of Ginkgo. 



Pollination-mechanism in Ricinus.* — C. Steinbrinck has examined 

 the anthers of Ricinus in order to test the statements made by Ludwig 

 and Delpiuo as to the distribution of the pollen. The author finds that 

 not only are these statements correct, but that we have here a phe- 

 nomenon analogous to that found in the sporangia of Ferns and Selagi- 

 nellas. The splitting of the anthers is due to a cohesion-mechanism, 

 but the right-sided splitting is not so certain as in the ferns, and the 

 means by which it is brought about is less well marked. As in the 

 ferns, the anther-walls, at the time of pollen-ripening, consist of only a 

 single layer of cells, and the outer epidermis is entirely absent. The 

 reason for this behaviour of the anthers is not at present evident. 



Germination of Seeds of Parasitic Plants.f— M. E. Heinricher 

 summarises the results of his investigations into the seed-germination of 

 parasites, especially of the Rhinanthere. The following aspects of the 

 germination processes are considered : — 1. The seeds of some species 

 will not germinate unless placed in contact with the roots of a suitable 

 host. Such are the seeds of Lathrsea (L. squamaria and L. claudestina) 

 and of Tozzia (T. alpina). In other cases, — e.g. Euphrasia (sens, lat.), 

 Alectorolophus, Bartschia — germination occurred by planting in a pot 

 containing soil free from all host-tissues. 2. Conservation of germina- 

 ting power by dried seeds. In some cases — e.g. Melampyrum pratense — 

 the seed will not germinate if dried for a short time. The same applies 

 to Thesium, Lathrsea, and Tozzia. The seeds of the latter germinate 

 entirely enclosed in the nut-like fruit, the radicle and plumule ultimately 

 bursting the fruit-wall. Cotyledons are never produced above ground : 

 development for the first two or three years is holoparasitic and sub- 

 terranean ; a subaerial leafy shoot appears ultimately, and the plant 

 flowers, fruits, and dies, the whole of its subaerial existence occupying 

 but a few weeks. The seeds of Thesium, and of Santalum album, would 

 not germinate unless planted in the soil enclosed in the fruit. Others of 

 the Santalacese were, however, found to be less sensitive ; seeds of 

 Osyris and Gommandra, sent in a dried state from Calcutta, were made 

 to germinate successfully. In disagreement with Gautier, the author 

 finds that drying does not destroy the power of germination in the 

 Rhinantheas generally, nor in PedicvJaris. He agrees with G-autier in 

 concluding that sensitiveness to drying depends upon the degree of 

 development of the embryo. 3. The season of germination is very 

 irregular. In the case of Lathrsea, germination may occur in the autumn 



* Ber. Bot. Gesell., xxviii. (1910) pp. 2-7. 

 t Rev. Gen. Bot., xxi. (1909) pp. 329-34. 



