68 SJMMAl.Y OF CUKRENT EESEARCHES RELATING TO 



perhaps in June during rainy years. 9. After fertilization the embryo 

 grows rapidly during July and develops into a pyriform body enclosed 

 in the calyptra. 10, By the middle of August the differentiation into 

 archesporium and exothecium is visible, and the calyptra has now ceased 

 developing. 11. About August 15 the archesporial cells usually differen- 

 tiate into spore-mother-cells and elater-forming cells ; also the capsule, 

 seta and foot begin to be evident. 12. By the end of August the sporo- 

 gonium is fully formed and the exothecium consists of two layers. 

 13. Early in September the spore-mother-cells all become lobed, and they 

 remain in the lobed condition tliroughout September and October ; and 

 in October spiral thickenings appear on the walls of the elaters. 14. By 

 the middle of November the oval spores have become separate, and by 

 the end of the month they have become multicellular. 15. The spores 

 remain unaltered until shed in April. 16. xifter germination the de- 

 velopment of the plants advances more quickly in moist than in dry 

 situations. 17. Plants in a very moist habitat are apt to be sterile, and 

 the best fruited plants occur on drier soil. 



o o 



Chemotaxis of Marchantia-spermatozoids.* — A. Akerman writes 

 of the chemotaxis of 3Iarchantia-s\)ermatozoids. These are excited 

 prochemotactically by potassium, rubidium, and caesium salts as well as 

 by proteid matters. The minimum action for potassium salts lies at 

 about yoVo ^lol- ; its strength must be forty times that of the sur- 

 rounding medium for potassium salts, and twenty times for proteid 

 matters. Potassium salts and proteid matters acting on Marchantia- 

 spermatozoids call forth quite different 'acts of ^perception. Sodium 

 and calcium salts have no chemotactic action on i/arr/; a?? //a-spermato- 

 zoids. On the other hand, magnesium and ammonium salts have a weak 

 action, while the other metallic salts cause strong repulsions. Every 

 kind of movement caused by salts is of a chemotactic nature. Osmo- 

 tactic irritability appears to be completely absent in these spermatozoids. 

 On the other hand, as Lidforss has already shown, they exhibit an 

 evident aerotaxis. 



Abnormality of Moss-capsule. t — H. N. Dixon describes some curious 

 instances of abnormality in the sporogoninm of AcanthoclacUiim laxi- 

 textmn, a moss collected in Darjeeling. Nearly 50 p.c. of the cap- 

 sules appear to be provided with a very slender elongate spur projecting 

 down from the base. Careful examination showed this to be no spur, 

 but a strand split off the seta. As to how the splitting takes place, 

 Dixon offers some theories, preferring the one that it arises from torsion 

 of the seta, or rather from tendencies to torsion in opposite directions, 

 resulting in rupture of the tissues. 



Galls and Malformations in Mosses. | — F. Matouschek publishes 

 notes on some malformations in mosses noticed in Moravia. Nematodes 

 galls were found on Anomodon longifoUus, Fseudoleslcea atrovirens, Leslce- 

 catemilata, Dicrnnnm lonfjifolium. Abnormal formations were found on 



* Zeitschr. Bot., ii. (1910) pp. 94-103. 



t Eev. Bryolog., xxxviii. (1911) pp. 121-4 (figs.). 



1 Zeitschr. Miihr, Landesmus. Eriinn, x. (1910) pp. 272-80 (figs.). 



