ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 993 



all cases it is the upper one only wMcli becomes a seed, this only is 

 described. 



The author then describes in detail the development of ovule and 

 embryo-sac both before and after fertilization. The cell which is cut oif 

 from the archesporial cell does not lie, as is usual, at the micropjlar, 

 but at the oj)posite end of the embryo-sac mother-cell ; and another most 

 anomalous appearance is to be seen at the base of the embryo-sac after 

 fertilization. The lowest cap-cell elongates until it has considerably 

 outstripped the embryo-sac in length ; further, it becomes divided by a 

 longitudinal median wall into symmetrical halves. The " appendage," as 

 the author denotes this structure, consists therefore of two very long 

 tapering cells, applied side by side, and ensheathed in the down-growing 

 ovular tissue. 



In the earlier stages after fertilization no formation of endosperm 

 takes place in the micropylar region of the embryo-sac. This region is 

 occupied by the synergid^e, which, instead of dwindling after fertilization 

 in the usual manner, go on increasing in bulk. By the time the seed is 

 ripe, they have become so large as to constitute a conspicuous tubercle at 

 the top of the seed. They have a granular protoplasm, often highly 

 vacuolated, and each has a large nucleus. Dr. Oliver suggests that these 

 enlarged synergidae assist in the absorj)tion of the food-material for the 

 placenta. 



In Trapella the cap-cells normally all lie below, i. e. at the chalazal 

 end of the embryo-sac, and not at its micropylar end. It is the upper- 

 most cell of the row which becomes the embryo sac ; a structure almost 

 unique among known plants. The author points out analogies in some 

 respects in the development of the embryo-sac in Loranthus, Asarum, and 

 Crocus, but in no other case do we meet with a persistent enlarged cap- 

 cell, as in Trapella. 



As to the affinities of Trapella : though coming in touch with 

 Myoporineas in the form and arrangement of the seeds, it is sej)arated 

 therefrom by its eminently pedalinaceous fruit and opposite leaves. None 

 the less Trapella forms a connecting link between the two somewhat 

 artificially separated cohorts of the " Genera Plantarum," namely the 

 Personales and Lamiales ; Pedalinese being placed with the former, 

 MyoporincEe with the latter. Trapella must, however, rest in Pedalinefe, 

 forming the only genus in a new tribe Trapellese. 



p. Ph.ysiolog'y.* 



(D Keproduction and G-ermination. 



Cross-fertilization.f — Mr. A. G. Foerste describes the structure of 

 the flowers of the following American species in connection with their 

 adaptation for cross-fertilization by insects : — Silene pennsylvanica and 

 regia, Sahbatia angularis, Psoralea Onohrychis, Desmodium canescens, 

 Lespedeza violacea, Tecoma radicans, Mimulus alatus and ringens, 

 Scropliularia nodosa, Buellia strepens, Pycnardhemum lanceolatum, 

 Monarda fistulosa, Brunella vulgaris, and Stachys cordata. 



* This subdivision contains (1) Reproduction and Germination; (2) Nutrition 

 and Growth (including Movements of Fluids) ; (3) Irritability ; and (4) Chemical 

 Changes (including Respiration and Fermentation). 



t Bot. Gazette, xiii. (1888) pp. 151-6 (1 pi.). 



