ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 321 



the food-material in the cavity of the megaspore on the formation of 

 the prothallium. It enlarges greatly as development proceeds, retaining 

 its position beneath the prothallium, and at time of fertilisation is much 

 larger than the nuclei of the remaining tissue, and the shape, which 

 varies considerably, is peculiar. It shows long arms and fine extensions 

 radiating towards the prothallium. As development proceeds it frag- 

 ments amitotically ; the reticulum is throughout very dense, and a 

 nucleolus is present. If the radiating processes arc normal, as seems 

 probable, they recall the filaments extending from the nucleus into the 

 food-mass in the egg-cells of Dytiscus (see AVilson, The Cell, p. 115). 

 In the case of liars ilia, however, the processes extend towards the tissue 

 to be nourished instead of towards the food-material. The nucleus is 

 doubtless concerned with the elaboration or transference of food- 

 material. 



Opening Mechanism of the Macrosporangia of Selaginella.* — 



S. Schwendener maintains that the dehiscence of the sporangia is due, 

 at any rate in part, to the hygroscopic action of a row of thin-walled 

 cells on the keels of the sporangia. In his opinion Steinbrinck t errs 

 in regarding a " cohesion mechanism " as the only possible cause ; 

 whether it plays any part in the process must be at present left un- 

 decided. 



Bryophyta. 



Formation of Antherozoids in Marchantia. J — S. Ikeno gives a 

 summary describing the behaviour of the centrosomes during the cell- 

 division that occurs in the formation of the antherozoids in Marchantia 

 polymorpha, and the relation of the centrosomes to the cilia of the 

 antherozoids. The blepharoplasts of the Vascular Cryptogams and 

 Gyinnosperms are, he thinks, to be regarded as centrosomes. 



Culture of Hepatics.§ — W. Benecke has experimented with the 

 development of the gemma? of Lunalaria cruciata when sown on 

 nutrient solutions of various constitutions, and has noted the effect of 

 the presence or absence of various salts, such as nitrates and phosphates, 

 upon the young plants. When cultivated in pure distilled water, the 

 plants barely produce any rhizoids ; they require the presence of chemical 

 stimulants, whether nutrient or otherwise, for normal germination. The 

 effect of the presence or absence of light upon the cultures is described. 

 The behaviour of these gemma? is compared with that of germinating 

 plants of Riccia fluitans and of the higher plants. The formula? of the 

 solutions employed, the modifications introduced, and the consequent 

 results, are detailed. 



Scapania.|| — C. Massalongo has made a study of the Italian species 

 of the genus Scapania, paying special attention to the many inter- 

 mediate and transitional forms which render so difficult any attempt to 

 make a satisfactory delimitation of the species. He recognises twenty 



* S.B. K. Preues Akad. Wiss. Berlin, xlvii. (1902) pD. 10.iG-9 (2 figs, in text). 



t See this Journal, 1902, p. 4n9. 



% Comptes Rendus. cxxxvi. (1903) pp. 628-9. 



§ Bot. Zeitschr., 1903. pp. 19-46 (6 figs, in text). 



il Malpighia, xvi. (1902) pp. 393-438. 



