ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 371 



reference to the two lower cells of the tetrad and the tissues derived 

 from them. The author finds that the proembryonic tetrad is compar- 

 able with that of Myosurus minimus and the greater number of the 

 Kauunculaceaj, but that the two lower cells of the tetrad have a very 

 different destiny. In CapseUa the intermediate cell gives rise to the 

 hypophysis and to the six cells at the distal end of the suspensory fila- 

 ment; the four cells forming the proximal portion of the latter, together 

 with the large micropylar vesicle, are derived from the lowest cell of the 

 tetrad. It will thus be seen that both cells take part in the formation 

 of the suspensor. In this respect CapseJla differs from Myosurus where 

 the two lower cells give rise to two distinct portions of the proembryo — • 

 i.e. one cell is entirely concerned with the formation of the hypophysis, 

 while the other develops into the short thick suspensor. It seems 

 unlikely that the conditions of cell-division in the tetrad of CapseUa are 

 the same in other members of the Crucifer^e. The work of other 

 >vi'iters appears to indicate that there are most important differences in 

 the development, number, order of formation and differentiation of the 

 cells of the suspensor. The author concludes that while the further 

 development of the upper cells of the tetrad is very constant, a careful 

 study of the development of the lower cells would throw considerable 

 light upon the comparative embryogeny of this family, and would prob- 

 ably prove of great use in the determination of affinities. S. G. 



CRYPTOGAMS. 



Pteridophyta. 



Apogamy in the Cyatheacese. — Alma G. Stokey {Bot Gaz., 

 1918, 65, 97-102, 10 figs.). An account of a few cases of apogamy 

 observed for the first time in the Cyatheaceaj. The method adopted 

 for obtaining pure cultures is described ; and the factors which may or 

 may not cause apogamy are discussed — namely, intense light, high 

 temperature, drought, bad culture, physiological conditions. Apogamy 

 was discovered in Dicksonia squarrosa, Cyathea muricata and 0. Tussacii ; 

 and the anatomical conditions observed in each case are described and 

 figured. A. G. 



Observations on the Tuber of Phylloglossum. — T. G. B. Osborn 

 (An?i. of BoL, 1919, 33, 485-516, 1 pi. and figs.). Pkylloglossum 

 Drummondii occurs in South Australia as a member of the geophytic 

 element in the flora of an area subject to prolonged summer desiccation. 

 The average depth of the current tuber is about 1 cm., but may range 

 from the surface down to 2 cm. at least. Whatever the depth may be, 

 the growing plant tends to form its new tuber at an average depth of 

 1 cm. A new method of vegetative reproduction is described for the 

 plant — namely, a regeneration from leaves that are injured or have become 

 detached by accident. In such a case an adventitious cell mass is 

 produced near the proximal end of the leaf on the abaxial surface — in 

 fact, a sort of protocorm. On this latter a growing point is differentiated, 

 and from it is produced a tuber. Reasons are given for regarding the 

 protocorm and tuber as two distinct and independent structures. The 



2 c 2 



