ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 209 



leaf. Immediately on escaping from the prothallium it forms a proto- 

 corm, apparently in the same way that the adult plant forms its annual 

 tuber. The first leaf gmws upwards, attaining a height of 2 to 5 mm. 

 above the ground. No root was formed during the first year of growth ; 

 the sporophyte seemed to depend largely for its moisture upon the pro- 

 thallium. Sometimes rbizoids are formed on the protocorm and its 

 pedicel. The first leaf has exactly the structure of a small leaf as pro- 

 duced in later years. Further development of the sporophyte seems to 

 be slow ; in many cases the plant comes up a second and third year with 

 only one leaf. 



On the whole the prothallium of Phylloglossum probably most re- 

 sembles one of the Lycopodium cernuum type, though it lacks the leaf-like 

 assimilatory lobes of the latter. It may perhaps be regarded as the 

 simplest known type of the isosporous Lycopodinae. 



The author has also observed an occasional branching of the spike, 

 and frequently the production of two tubers, sometimes on opposite 

 sides, sometimes close together on the same side of the plant. He re- 

 iterates the view that Phylloglossum is a primitive, and not a reduced 

 type. 



Muscine8e. 



Leaf-Movements in Polytrichum.* — K. Giesenhagen gives au ac- 

 count of the late F. Stolz's researches into the movements of the leavts 

 of Polytrichum juniperinum, as controlled by moisture or drought. 

 Starting from the previous determinations of Firtsch and of Bastit as to 

 the actual tissues which contract or expand in response to the absence 

 or presence of water, Stolz demonstrated the important part played by 

 the transverse band of quadrate cells across the upper surface ot the 

 leaf at the line of transition from leaf-sheath to lamina. The walls 

 of these cells imbibe water ; the band of tissue expands and bends back 

 the lamina of the leaf until it stands at about a right angle with the 

 always appressed sheath. 



Structure of the Peristome, f — After a long interval, H. Philibert 

 resumes his study of the peristome of Mosses, and points out the 

 great variability in the structure of this organ within the same genus, 

 Buxbaumia. In B. indusiata the peristome has by no means always, or 

 even generally, the composite structure which has usually been ascribed 

 to it. It may even be reduced to the endostome, and this endostome 

 itself does not always consist of an entire cylindrical tube, but may be 

 broken up into a confused agglomeration of filaments. In this state it 

 presents a close resemblance to the peristome of the Dawsonieas ; and 

 there can be little doubt of the close affinity of the two families, the 

 Dawsonieae being the older. 



Mosses new to Britain. J — Messrs. Jones and Horrell describe and 

 figure an arctic and subarctic species, Tetraplodon Wormskioldii Liudb., 

 which they discovered fruiting on the summit of Widdy Bank Feli, 

 Durham, last August. The plant is common in all high northern 



* Flora, xc. (1902) pp. 305-15. | 



t Rev. Bryol., xxviii. (1901) pp. 127-30. Cf. this Journal, 1896, p. 545. 

 J Journ. Bot., 1902, pp. 49-53 (1 pi.). 

 April 16th, 1902 p 



