350 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Embryogeny of Thea. * — Among observations with regard to the 

 structure and development of the fruit of Thea chinensis by Dr. F. 

 Cavara, the following relate to the development of the embryo-sac and 

 embryo. The formation of the embryo-sac does not follow the usual 

 course in Apopetal® ; it is the first cell resulting from the division of the 

 initial cell which becomes the mother-cell of the embryo-sac. After the 

 impregnation of the oosphere a period of rest ensues, which may extend 

 to as much as eight months, during which the impregnated oosphere 

 behaves like a germinating spore. The suspensor is remarkably long, 

 and may consist of as many as 18 or 20 cells. The first division of the 

 mother-cell of the embryo is not longitudinal, as is usually the case, but 

 transverse. 



Embryo-sac of Sparganium.f — Prof. D. H. Campbell has investi- 

 gated the development of the flower and embryo-sac in several species 

 of Sparganium, especially in S. simplex, ramosum, and Greenii. 



The egg-apparatus is small in 8. simplex, and the polar nuclei fuse 

 completely before the " egg " is fertilised ; while in S. Greenii they 

 remain separate until after fertilisation. The antipodal cells are three 

 in number, and in S. simplex are very inconspicuous ; after fertilisation 

 there is a remarkable secondary growth in the antipodal cells, resulting 

 finally in a large cell-mass consisting (in S. simplex) of over 150 cells. 

 The suspensor remains undeveloped, as in Graminese. The embryo 

 undergoes three transverse segments, of which the terminal one gives 

 rise to the cotyledon, stem-apex, and a part of the root. The young 

 embryo is completely invested by the endosperm. The plerome of the 

 root is derived entirely from the terminal segment. The enlarged anti- 

 podal cells appear at first to perform the function of endosperm-cells. 

 The large endosperm-nuclei have often several nucleoles formed by 

 fragmentation of the original nucleole. Large crystalloids are abundantly 

 developed in the older endosperm-cells of S. simplex. 



As regards the systematic position of Sparganium, Prof. Campbell 

 does not consider it to be nearly allied to Typha, but to have a closer 

 affinity with the Gramineae than with any other family except possibly 

 the Pandanaceae. 



Embryogeny of Cephalotaxus.J — Heir W. Arnoldi finds the develop- 

 ment of the embryo in Cephalotaxus Furtunei to agree in several impor- 

 tant points with those already described in Taxus, § differing from that 

 in all other Gymnosperms at present known, and presenting a transition 

 from that of the oldest known Gymnosperms, the Cycadoideaa. 



The archegone has a two-celled neck and an ovum-cell. During the 

 growth of the latter it becomes filled with a peculiar albuminoid sub- 

 stance, formed in the nuclei of the covering layer with the assistance 

 of the nucleole, and being at first in the condition of small drops. When 

 these drops have passed from the cells of the covering layer into the 

 ovum-cell, they grow to a considerable size and acquire a complicated 

 structure, serving as the first nutrient substance for the developing 

 embryo. 



* Bull. Soo. Bot. ItaL, 1899, pp. 238-41. 



t Proc. California Acad. Sci., i. (1899) pp. 293-328 (3 pis.). 



J Flora, lxxxvii. (1900) pp. 46-63 (3 pis.). § Cf. this Journal, 1899 p 504. 



