ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 189" 



The development of the cotyledon in Corydalis and Ficaria is on the 

 same lines in the two genera ; there is scarcely a trace of a second 

 cotyledon. In Corydalis cava, G. nobilis, and G. lutea a considerable 

 increase in the endosperm takes place before germination. Idioblasts 

 occur in very young embryos. 



Morphological Study ; of Thuja* — W. G. Land has studied the 

 gametophyte stage, fertilisation, and embryology in Thuja occidentalis in 

 the vicinity of Chicago. No prothallial cells could be demonstrated in 

 the pollen-grain, the next step after the separation of the tetrads being 

 the organisation of a tube nucleus and a generative cell. Before the 

 appearance of the archegonium initials the penetration of the pollen-tube 

 is relatively slow, but now becomes rapid, the tube piercing the remaining 

 rows of nucellar cells and spreading over the archegonia absorbs the 

 remnants of the neck-cells and lays bare the upper ends of the eggs. 

 The body-cell divides into two equal and functional male cells. 



There are generally six archegonium initials ; the neck consists of 

 two to six cells formed by anticlinal divisions only, they are soon almost 

 entirely absorbed by the central cells. Protoplasmic connections between 

 the jacket cells and central cells were not seen. A ventral nucleus is 

 cut off and lies free in the cytoplasm in the upper part of the egg. 

 When an archegonium has not been fertilised there are indications that 

 the ventral nucleus divides. There are frequent instances of a further 

 (mitotic) division after fertilisation, and there is evidence that both the 

 ventral nucleus and the egg in an archegonium may be fertilised. 



In most cases the tube and stalk nuclei from the pollen-tube do not 

 enter the egg but disorganise in the space above the archegonia. The 

 fusion nucleus is in general below the centre of the egg where it remains 

 until the first division is completed. The two nuclei then sink to the 

 bottom of the egg and divide simultaneously, while the ventral has 

 enlarged considerably and is quite conspicuous. Eight free nuclei are 

 formed in the proembryo which become separated by a transverse wall 

 into two groups, each of four nuclei ; the nuclei of the lower group are 

 completely walled in and from these the single embryo develops. The 

 upper nuclei are exposed to the cytoplasm above. The latter divide to 

 form two tiers, the lower of which elongates to form the four suspensors 

 by which the embryo is thrust down into the endosperm. 



Fruit of Jacquinia ruscifolia and Trichomes in Myrsinacese.f — 

 L. A. Mennechet describes the anatomy of the fruit and the histology 

 of the pericarp and seed of Jacquinia ruscifolia, and also the structure 

 and development of the hairs, glandular and non-glandular, in this and 

 other genera and species of the order Myrsinaceae. 



Physiology. 

 Nutrition and Growth. 



Influence of Carbonic Acid Gas on Growth.! — P. Chapin finds 

 that the optimum amount of C0 2 in the air for growth in the higher 



* Bot. Gazette, xxxiv. (1902) pp. 249-58 (3 pis.). 



t Journ. de Bot., xvi. (1902) pp. 349-57 (3 figs, in text). 



X Flora, xci. (1902) pp. 348-79 (1 pi.). 



