194 SUMMARY OF CURRENT RESEARCHES RELATING TO 



exactly comparable with that of the pollen-mother-cell. The lowest of 

 the four cells becomes the embryo-sac, which develops in the typical way, 

 the two polar nuclei fusing together before pollination. From the 

 author's study of embryo development the views of Wille, as against 

 those of Ascherson, are supported. 



Embryology of Juncaceae.* — M. Laurent gives the following account 

 of the development of the embryo. The fertilised egg divides trans- 

 versely into two unequal cells, the upper and larger of which constitutes 

 the greater part of the embryo ; the lower or suspensor cell divides 

 transversely. The upper of the two daughter-cells again divides in 

 the same sense, and from the uppermost of the three suspensor cells 

 is formed by vertical walls a plate, which separates the developing 

 embryo-cell proper from the two lower suspensor cells, which increase 

 considerably in size. Further development consists in the formation of 

 a large cotyledon from the embryo-cell, a radicle from the upper portion 

 of the suspensor, while the two large suspensor cells completely dis- 

 appear. The plumule appears at the base of the cotyledon above the 

 radicular meristem. The hypocotyl is suppressed. 



Goebel and other authors have referred to the embryo of Juncus as 

 undifferentiated. M. Laurent, however, has studied the development 

 here described in several species of Juncus and also in Luzula. The 

 suspensor plays an important part : reduced at first to a few cells, it 

 develops tardily, but subsequently becomes the chief centre of cell 

 activity and forms the radicle. The cap does not develop till after the 

 exfoliation of the two or three lower elements of the suspensor. 



Poindexter, C. 0. — The Development of the Spikelet and Grain of Corn. 



[As a preliminary to the study of xenia in maize, the author describes the 

 development of the pistil and fruit.] 



Ohio Naturalist, iv. (1903) pp. 3-9 (2 pis.). 



Physiology. 

 Nutrition and Growth. 



Influence of Potassium on the Morphology of Sterigmatocystis 

 nigra.f — M. Molliard and H. Coupin are of opinion that data as to the- 

 influence of culture media on the growth of fungi have not been accu- 

 rate enough to be of scientific value. They have therefore selected 

 potassium, one of the ingredients in an artificial solution, and tested 

 the effect of its presence or absence on the morphological development 

 of Sterigmatocystis. The absence of the salt, potassium carbonate, had 

 an immediate effect, especially on the fertile hyphrc. The sterigmata 

 instead of bearing conidia grew out into mycelial filaments, and on 

 these were formed secondary smaller conidia-bearing heads. Forms 

 resembling Aspergillus and Penicillium were also developed, and the 

 conidia when formed in the absence of the potassium Avere invariably 

 small and the wall less cutinised. Also the conidia germinated readily 

 in situ and produced chlamydospores. 



* Comptes Eendus, cxxxvii. (1903) pp. 532-3. 

 t Rev. Gen. Bot., xv. (1903) pp. 401-5 (1 pi.). 



