140 RE(X)RD OF CURRENT RESEARCHES RELATING TO 



cells in which they were formed, becoming normal resting-spores ; but 

 till attempts to induce them to germinate failed. 



Sub-aerial Alga.* — The form Chroolepus jolithus Hg. has been 

 submitted to a careful examination by Professor Schnetzler. His 

 specimen grew on the surface of gneiss in the Chamounix valley : 

 it has also been noticed in the Harz, on a siliceous rock, which 

 owes its name, " Violet Stone," to the odour of violets which the alga 

 exhales when damp. 



It consists of simple or ramified series of thick-walled cells, 

 whose terminal members develop biciliated zoospores within them. 

 By the side of the cells a quantity of yellow oil-drops occur, which 

 are derived from the cells, as is shown by the treatment of these last 

 by borax ; when the protoplasm contracts and the red investing liquid 

 — which is coloured blue by iodine — escapes as red oil-drops : alcohol 

 also produces the yellow oil from the cells. 



The chlorophyll appears to be masked by the oil which becomes 

 manifest in the protoplasm after the action of borax. Oil thus 

 appears here to replace the starch of other plants ; it also occurs in 

 the chlorophyll-grains of Strelitzia and Musa. 



Development of Sphserotilus natans and its Relationship to 

 Crenothrix and to Bacteria.t — At a weir near Breslau, E. Eidam 

 observed great quantities of mucilaginous and slimy light-brown 

 patches of an alga which he identified as Sphcerotilus natans Ktz. In 

 its vegetative condition the filaments are remarkably long, colourless, 

 and not club-shaped at the extremity like Crenothrix, but of a uniform 

 diameter throughout. Each filament is divided into a large number 

 of long cells tilled with a homogeneous j^rotoplasm. The entire 

 filament is inserted in a colourless sheath. It is never endowed with 

 motion, but often breaks up into fragments, and multiplies, like all 

 leptothrix forms, by the develoj)ment of the separate fragments into 

 new filaments. No incrustation with iron has been observed, like in 

 Crenothrix. But another very remarkable mode of reproduction was 

 observed in the filaments of Sphcerotilus, accompanied by a striking 

 change in colour. The cells become opaque, and the w^hole mass of 

 a milky appearance ; the protoplasm collects into a large number of 

 extremely small and strongly refractive balls. Each cell becomes 

 thus transformed into a sporangium, and the protoplasmic balls are 

 spores, each of which may develop into a new filament. In mass the 

 spores are of a brick-red and finally a brown-yellow colour. When a 

 number of spores fail to germinate, the mass has the structure of a 

 zoogloea-colony, and resembles the palmella condition of Crenothrix. ^ 



The writer does not, however, agree with the conclusion of 

 Cienkowski that the groups of bacteria distinguished by Cohn are 

 generically identical. He believes, on the contrary, that there may 

 be a very large number of distinct organisms, each of which may 

 have its bacterium- and its leptothrix-condition, although the cycle of 

 development of many is at present but very imperfectly known. 



* ' Bull. Soc. Vaud. Sci. Nat.,' xvi. p. 247. 



t 'SB. hot. Ver. Prov. Brandenburg,' April 2.5, 1879; sec 'Bot Zcit.,' xxxvii. 

 (1879) p. 724. X ^ee this Journal, ii. (1879) p. 925. 



