ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 557 



emergences, aud ajiiiear in ascending order in more or less regular 

 series, in L. hidbosa, tliey are develoj^ed on the bulb, the stalk, and the 

 basal parts of the lamina. The stalk may be divided into five regions, 

 viz. : — (1) the primary fixing-organ, (2) the bulb, (3) a flattened 

 twisted portion, (4) a portion with flounced ed,G;es, and (5) a flat straight 

 piece which passes upwards into the lamina. The principal purpose of 

 the bulb appears to be the fixing of the p]ant to the sea-bottom. It also 

 serves to produce sporanges ; so that, if the rest of the plant is torn 

 away by storms, there is still left in the bulb the power of assimilation 

 and of reproduction. L. hulbosa is jirobably an advanced type, with a 

 large amount of differentiation and complicated attempts at adaptation. 



Contraction of the Chlorophyll-bands of Spirogyra.* — Herr H. de 

 Vries finds that several species of Spirogyra (notably S. communis and 

 nitida), when the filaments hibernate, have the chlorophyll-bands con- 

 tracted ; but that this is not the consequence of injury is shown by the 

 continued turgidity of the cell and movement of the protoplasm-granules, 

 as well as by the impermeability of the tonoplasts to eosin and plas- 

 molytic reagents during the contraction. When the contraction of each 

 separate band begins at one or at both ends, the bands simply break up 

 into small portions which lie on the line of the original bands. But 

 when, in a compound spiral, like that of ;S^. communis, the middle coils 

 contract, while the outer ones retain their original position, the cylin- 

 drical tonoplast becomes more or less deeply constricted in a variety 

 of ways. 



Variation in Desmids.f — ^M. E. De Wildeman describes and figures 

 a number of varietal forms of species belonging to the genera Micrasterias 

 and Euastrum, and believes that a large number of these variations are 

 the result of reduplication or division, especially when this takes place 

 before the half-cells have attained thfeir full development. He considers 

 also that it is impossible to ignore the existence of geographical races of 

 the same species. 



Spongocladia.J — Messrs. G. Murray aud L. A. Boodle referring to 

 Marchesetti's observations § on the symbiotic relationship of a sponge 

 and an alga in the case of Marchesettia spongioides, consider that this 

 discovery confirms the probability of a similar phenomenon being 

 presented also by Spongocladia. 



Urospora.|| — Herr G. Woltke does not agree with Areschoug's later 

 identification of his Urospara mirahilis with the genus Hormiscia, but 

 regards it as constituting a distinct genus of Ulotrichacese. It grows on 

 rocks which are occasionally sprinkled with salt water. The filament 

 is unbranched, and consists of cylindrical thick-walled cells of very 

 variable size and form. One or more basal cells, of greater length but 

 smaller breadth, and destitute of chlorophyll, constitute a rhizoid. The 

 green cells contain a single chromatophore which encloses a number of 

 pyrenoids. The megazoospores are pear-shaped, with 4 cilia at their 

 broader colourless rounded end, from 14 "5 to 25 /x long, and from 5*8 

 to 9 fji broad, a large number being contained in a mother-cell, where 



* Ber. Deutsch. Bot. Gesell., vii. (1889) pp. 19-27 (1 pi.), 

 t Bull. Soc. E. Bot. Btlgique, xxvi., part i., 1887 (1889) pp. 271 88 (1 pi.). 

 t Ann. of Bot., iii. (1889) pp. 129-31. Cf. this Journal, 1888, p. 1002. 

 § Cf. this Journal, 1885, p. 282. 



II Schrift. Neurussisch. Naturf. Gesell. Odessa, xii., 53 pp. and 2 pis. See Bot. 

 Centralbl., xxxviii. (1889) p. 483. 



1889. 2 Q 



