42 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Structure and Development. 

 Reproductive. 



Studies on the Aracese.* — D. H. Campbell makes a further con- 

 tribution to our knowledge of the gametophyte, and the embryology of 

 the Araceae, by the study of a variety of Anthurium violaceum and 

 Nephthytis liber ica. Anthurium closely resembles the usual angio- 

 spermous type : the archesporium is a single hypodermal cell, which 

 divides periclinally ; the primary sporogenous cell becomes the megaspore 

 without division ; there is no free nuclear division in the formation of 

 endosperm, which proceeds from the antipodal towards the micropylar 

 end of the sac ; the embryo originates as an almost globular mass of 

 cells with a rudimentary suspensor. In Nephthytis, on the other hand, 

 there is considerable variety ; the archesporial cells are variable in 

 number, and generally more than one embryo-sac begins to develop ; 

 the form of the mature sac varies widely, in some cases containing only 

 two nuclei, in others twelve or thirteen. The author reiterates his 

 conviction that the Araceae are relatively primitive monocotyledons. 



Microspores of Araucaria Bidwillii.f — G. Lopriore describes a 

 multinuclear condition in the pollen-grains of this species. He finds 

 that the spores germinate best in darkness in a 12 p.c. sugar solution, 

 the pollen-tubes reaching their greatest length in 8-10 days. As the 

 spore germinates, two lens-shaped cells are cut off ; these divide to form 

 a mass of about 15 cells, the walls of which soon disappear, leaving the 

 nuclei free in the general cytoplasm. By further nuclear division 

 the number is increased to 20-41 nuclei, 36 being the most frequent. 

 Division ceases when the pollen-tube begins to develop. The author 

 regards as vegetative nuclei two somewhat larger nuclei in the end of 

 the tube, while the others are regarded as equivalent to spermatozoids. 

 C. J. Chamberlain, $ however, in reviewing Lopriore's work, suggests, 

 from an examination of the figures, that the two larger nuclei are the 

 male nuclei, while the rest of the numerous nuclei represent an unusual 

 prothallial development. 



Physiology. 

 Nutrition and Growth. 



Germination of Seeds of the Castor-Oil Plant.§ — J. Reynolds 

 Green and H. Jackson have made a series of observations which supple- 

 ment the earlier researches of the former author. Their experiments 

 show that germination is associated with a remarkable activity of the 

 cells of the endosperm, which spring into renewed life and set up a very 

 complex metabolism. Their protoplasm grows and takes a prominent 

 part in these metabolic changes, secreting enzymes and setting up 

 various chemical changes in the cells, partly by means of the enzymes 

 and partly independently of them. The embryo also contributes to the 



* Ann. of Bot., xix. (1905) pp. 329-49 (4 pis.). 



t Ber. Deutsch. Bot. Ges., xxiii. (1905) pp. 335-46 (1 pi.). 



\ Bot. Gazette, xl. (1905) p. 391. 



§ Proc. Roy. Soc, Series B, lxxvii. (1905) pp. 69-85. 



