662 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The seed of Galium tricorne affords a different type of ferment action. 

 The thick and irregularly pitted -walls of the endosperm are richly pro- 

 vided with connecting threads which are usually arranged in barrel- 

 shaped groups. No distinction can be drawn between the groups of 

 threads which occupy the pit-closing membranes and those which occur 

 in thick parts of the walls, since every gradation from one to the other 

 occurs. The walls are apparently composed of a substance of the 

 nature of pecto-cellulose. The progress of the ferment action is not 

 centrifugal as m Tamus, as the ferment appears to originate in the 

 endosperm and inwards towards the embryo in a centripetal manner. 

 The relation between the progress of the ferment action and distribution 

 of the connecting threads is not always clear, as in many cases the dis- 

 solution of the walls appears to take place without any obvious con- 

 nection with the threads. The authors conclude that although the 

 ferments can attack and dissolve the thick walls of the endosperm 

 ■without any necessary relation to the connecting threads, yet that in 

 the initial stages the penetration of the enzyme may be effected by 

 means of the threads which thus afford a means of reaching the internal 

 parts of the wall. Secondly, that the connecting threads are concerned 

 mainly and primarily with the conduction of food and stimuli from the 

 parent plant to the developing embryo and endosperm of the seed, and 

 that any further use to which they may be put during germination 

 must be regarded as only of secondary importance. 



Comparative Embryology of the Rubiacese.* — F. E. Lloyd formu- 

 lates the following conclusions from a study of twenty-three species re- 

 presenting nine genera of the Rubiaceae. The ovules have a single 

 integument and a greatly reduced nucellus, which ca7i be distinguished 

 only at an early age when it forms a cap of a single layer of cells 

 crowning the archesporium. In the Spermacocese there is, in addition 

 to the integument, a second outgrowth, derived from the fimicle, — a 

 strophiole ; it contains the vascular supply of the ovules and includes 

 also numerous special excretory cells which become loaded with raphides. 

 Similar cells occur in some Galiese near the embryo-sac for some time 

 before and after fertilisation ; the calcium oxalate may, the author sug- 

 gests, be of some positive value. Houstonia differs from the other 

 genera studied in that each loculus contains a number of ovules, not a 

 solitary one ; the ovules are relatively very small and borne on a club- 

 shaped placenta. They have no integument, and the archesporium, 

 which consists of but one functional embryo-sac mother-cell, becomes 

 deeply buried in the nucellar tissue by the growth of the capping cells. 

 The author points out that the belief that a single naked ovule is 

 correlated with the parasitic habit must be rejected. Except in Hous- 

 tonia the archesporium contains 7 to 15 megaspore mother-cells, each 

 of which, except the arrested ones at the side of the archesporium, 

 divides to form four megaspores which are generally not separated by 

 walls. This condition is comparable to that described as occurring in 

 Eichhornia and Avena. All the megaspores are both morphologically 

 and physiologically equivalent. The author refers to Koernicke's view 

 of the fact that the embryo-sac cell in the great majority of seed plants 



* Mem. Torr. Bot. Club, viii. (1902) pp. 1-112 (15 pis. and 11 figs.). 



