318 SUMMARY OF CURRENT RESEARCHES RELATING TO 



they themselves are but slightly affected. The behaviour of the tube 

 seems to indicate that a chemotactic influence, arising either in the egg- 

 apparatus or in the egg itself, determines the course of the tube, and 

 also favours the view that the intercellular mode of growth is a physio- 

 logical phenomenon and not an inherited character. 



" Filiform-apparatus " of the Angiosperms.* — A. Habermann has 

 examined Gladiolus, Yucca, Fankia, Ranunculus, Aconitum, Thalic- 

 trum, etc., with special reference to the so-called filiform-apparatus. 

 He finds that the synergidffi possess a fihform-apparatus, which, although 

 varying in size and distinctness, is always of similar character. Thalic- 

 truni purpurascens can reproduce by apogamy, and here the filiform- 

 apparatus is much swollen. Before fertilisation, the upper parts of the 

 synergid« usually have a dome-like appearance ; later on, the membrane 

 of the embryo-sac in this region is absorbed, and the filiform-apparatus 

 protrudes. After fertilisation, both synergidas and filiform apparatus 

 perish, but remain as a shapeless mass in the micropylar region. Simul- 

 taneously with the development of the filiform-apparatus, vacuoles appear 

 in tlie lower parts of the synergidie, and it is highly probable that these 

 vacuoles secrete a chemotactic substance, which issues through the 

 filiform-apparatus. 



Embryo-sac of Phaseolus vulgaris. f — C. de Bruyne has investigated 

 the embryo-sac of Phaseolus vulyaris, and is led to the conclusion that 

 those authors who regard the albumen as nothing but nuclei scattered 

 in a parietal plasmodium, are only correct in regard to the very young 

 embryo-sac. From the time when the embryo becomes globular in 

 form, cell-formation in the neighbourhood of the embryo can be 

 clearly seen. These cells are uninucleate and usually spherical. There 

 are two cavities in the embryo-sac — an upper embryonic cavity en- 

 closing the embryo, and a lower nutritive cavity. Botli cavities are 

 bounded by membranes derived from the albumen, that of the em- 

 bryonic cavity being formed of flat, thickened cells. The albumen-cells 

 of the nutritive cavity travel towards the dividing membranes, and 

 gradually become liquefied ; and the author believes that the thickened 

 membrane of the embryonic cavity acts as an osmotic medium for con- 

 ducting the albumen to the embryo. 



Embryology of " Shepherd's-purse." % — J. H. Schaffner has pub- 

 lished an unfinished paper deaUng with investigations upon the em- 

 bryology of " Shepherd's-purse." The entire embryo is developed 

 from the two outer terminal cells of the pro-embryo. The terminal 

 cell gives rise to the cotyledons, stem-tip and hypocotyl, while the 

 basal cell, after cutting off one suspensor-cell, gives rise to the calyp- 

 trogen, root-tip, and calyptra. The development of the calyptrogen 

 shows that it arises both from the terminal and basal embryo-cells. 

 The embryo is at first straight, but later on is forced round by the 

 curved wall of the ovule. The plerome consists of several small, 

 elongated cells, surrounded by a sheath of larger cells, and the periblem 



* Beih. Bot. Centralbl., sx. (190G) pp. 300-17 (1 pL). 



+ Bull. Acad. roy. deBelgique (Classe des Sciences), 1906, pp. 577-98 (2 pis.). 



X Ohio Nat., vii. (1906) pp. 1-7 (3 pis.). 



