62 SUiMMARY OF CLTJIENT RESEARCHES RELATING TO 



mature seed-cones like those of Cyc ideoidia Wielandi in most of the 

 leaf -bases near the apex of the trunk. The wb.ole structure strongly 

 recalls that of G. ttirrita, and nearly every seed contains a mature 

 embryo. All these three specimens, together with other less well- 

 preserved American fo.rsil seeds, show great homogeneity in testal 

 features, the only discernible differences being in the ribbing and size of 

 seeds, with some variation in the thickness of the tissue zones of the 

 seed-wall. The latter is composed of : 1. An outer coat formed from 

 an inner palisade layer and an outer tubular layer, both of which may 

 be reduced or eliminated. 2. A middle coat, which is not merely in- 

 durated or suberous, but undoubtedly stony in character, varies much 

 in thickness, and shares in the rib-formation of the outer coat. 3. An 

 inner fleshy coat of about the same thickness as the stony coat, and 

 formed of outer elongated and inner square or roundish cells with the 

 ancestral endosarcal bundle system still represented. Both of the outer 

 coats thicken towards the shoulder, and form a ribbed or tentacled corona 

 around the base of the micropylar tube. The author still regards 

 Lagenostoma as forming the nearest known analogy to the seed-structure 

 of the Cycadeoidea, and since existing Gymnospermous seeds, especially 

 those of the Abietinete, present clear analogies to this group, he also 

 favours the view that the Abietinea? are the most ancient of the Conifers. 



Embryo-sac and Endosperm in Seedless Persimmons.* — AY. L. 

 Woodburn has studied the fruits of unfertilized flowers of Diospyros 

 virginiana, i.e., seedless persimmons, and finds great variation in the 

 development of the embryo-sac. The latter is not always fully developed 

 before disorganization begins, although the egg-apparatus is always more 

 advanced than the antipodal cells. The polar nuclei come into close 

 contact, but have not been observed to fuse, further development being 

 frequently arrested at this stage by the intrusion of the integuments 

 into the cavity of the embryo-sac. Free nuclei form in the peripheral 

 cytoplasm and cell-formation follows, until the cavity of the embryo-sac 

 is more or less filled with endosperm, which is specially well-developed 

 around the egg-apparatus. It is doubtful what stimulus causes this 

 development of endosperm. The inner integument forms a definite, 

 nutritive jacket-layer of cells, and a relatively large portion of the 

 nucellus is persistent. 



Physiology. 

 Nutrition and Growth- 



Chlorophyll-formation. t — N. Monteverde and W. Lubimenko have 

 investigated the formation of chlorophyll in green plants, in order to 

 throw further light upon the theory enunciated by Liro, according to 

 which, chlorophyll-formation is a purely photo-chemical process, wheieby 

 a colourless chromogen (leucophyll) is transformed into a green sub- 

 stance, viz. chlorophyll. Experiments show that plants grown in dark- 

 ness form a yellow colouring matter and a special pigment, which, upon 



* Bull. Torrey Bot. Club, xxxviii. (1911) pp. 379-83 (1 pi.), 

 t Biol. Centralbl., xxsi. (1911) pp. 449-58. 



