Miscellaneous. 271 



to the phenomena of vegetable life is still further increased during a 

 state of immobility and repose through which the young Chromatia 

 sometimes pass. In fact, we often find great agglomerations of 

 these red vesicles bound together by a mucilaginous material ; they 

 then resemble those red sjiots which are sometimes formed upon 

 bread. When the agglomerations of which I have spoken are 

 observed for some time, a curious fact is noticed in them. A 

 breath of life seems to come to animate this inert mass. The 

 vesicles of which it is composed vibrate ; those of the margin 

 become detached and swim rapidly ; in this way the spot gradually 

 breaks up into young Chromatia, with which the water soon 

 swarms." 



Last autumn Prof. Forel brought me a red colouring-matter found 

 in suspension in the water of the Lac de Bret, which was coloured red 

 by it. Under the microscope I found irregular, lobate, rounded masses 

 of a red colour, formed by micrococci. Notwithstanding this state 

 of partial decomposition, I regarded this red matter as the zooglaea- 

 state of Beggiatoa roseo-persicina. I directed my preparator, 

 M. Tonduz, to look for the red colouring-matter this spring in 

 the water of the Lac de Bret ; but he did not find any of it. On 

 the other hand, however, in the eastern part of the lake, he saw a 

 material of a bluish-black colour, forming a streak of about 

 4-5 metres in length. The colouring-matter occurred especially in 

 the fissures of the ice, or at the boundary between the ice and the 

 water. 



On examining this material, 1 found in it a great number of 

 Diptera in process of decomposition ; they served as the starting- 

 points of long colourless filaments of Beggiatoa. This Leptothrix- 

 form was accompanied by blackish zoogloese and free micrococci. 

 At the first glance, the Beggiatoa taken on 3rd April in the Lac de 

 Bret resembles Beggiatoa alba, which, like B. roseo-persinica, develops 

 lapon animal and vegetable materials in decomposition ; but Zopf 

 himself states that when this latter species is decolorized it no 

 longer differs from the former. As M. Forel found Beggiatoa roseo- 

 persicina in the water of the Lac de Bret, I am disposed to refer to 

 that species the organism which produced the bluish-black coloration 

 found by M. Tonduz. 



In 1856 1 had already foi'eseen the relations which exist between 

 the zooglcTea- and leptothrix-forms oi Beggiatoa roseo-persicina. I had 

 observed a vegetable organism in the form of very thin filaments 

 which difi'used in the water red corpuscles animated by a peculiar 

 movement which strikingly resembled the first phases of Chromatium. 

 These red globules afterwards combined into masses which became 

 covered with filaments (lei<tothris-form). 



The masses of zoogloea observed in the blackish colouring- matter 

 of the Lac de Bret have presented the fact, mentioned doubtfully by 

 Zopf, that the cocci united into zooglssfe can produce filaments of 

 the leptothrix-form without passing through the bacillus-form. 



In the preceding observations we find facts which serve to support 



