270 Miscellaneous. 



north-east of Vevey. The water holding the red colouring-matter 

 in suspension swarmed with small organisms, which, under the 

 microscope, presented a fine rose-colour. They were of an elongated 

 form, rounded at the two extremities ; their average length was 

 0-01 millim., and their width ji^ millim. At that time I had 

 only a microscope of low power ; but the vortices of molecules 

 around these bodies led me to infer the presence of vibratile cilia. 



At the time of which I speak these little organisms were regar- 

 ded as Infusoria by zoologists ; Perty (' Zur Kenntniss kleinster 

 Lebensformen,' 1852) placed them in the genus Chromatium. 

 Their mode of reproduction even then led me to foresee their 

 vegetable nature. Eabenhorst ('Flora Algarum Europ.' iii. p. 28) 

 described these same organisms under the name of Pleurococcus 

 roseo-persicinus. Ray Lankester, Waring, and Zopf now class them 

 among the Schizomycetes. 



Zopf (' Zur Morphologie der Spaltpflanzen,' 1882) describes, under 

 the name of Beggiatoa roseo-persicina , Zopf, a Schizomycetan of which 

 the organism that I observed in siilphurous water of the Alliaz is only 

 a phase of development. Zopf distinguishes two principal forms of 

 Beggiatoa roseo-persicina : — 



1. The Leptothrix'form. — Very thin filaments, with the articu- 

 lation very indistinct or almost null in most of the length of the 

 thread, except at the base. These filaments are attached to jjlants 

 or animals in course of decomposition. They are usually of a rose- 

 or violet-colour ; sometimes they become nearly colourless, and 

 in this case they are not to be distinguished from Beggiatoa alba. 

 As in this last species, these filaments contain granules of sulphur. 

 By means of suitable colouring, however, it may be demonstrated 

 that they consist of small segments. In this way true micrococci 

 are obtained. 



2. The ZooglcBa-hrm. — The micrococci of the filaments of Beg- 

 giatoa separate by little and little, by rounding off' their angular 

 cells and dividing into two. According to their dimensions we 

 distinguish micrococci and macrococci, which I observed in the 

 water of the Alliaz. 



By the division and multiplication of these cocci gelatinized 

 colonies are formed, sometimes of a lobate form, sometimes mul- 

 berry-shaped, which are known by the name of zooglcea. The 

 colour of these colonies varies ; some are even colourless. The 

 cocci of the colonies of zooglaea can become transformed into bacilli- 

 form cells. According to an observation of Zopf's, the micrococci 

 of the zooglrese of Beggiatoa alba also became transformed into 

 bacilli, which, after swimming in the water, produced the Leptothrix- 

 form. Zopf adds that it appears that the micrococci of the zooglseae 

 can pass over the formation of bacilli and become elongated directly 

 into filaments. 



In my communication of 1856 I had already observed this forma- 

 tion of zooglsese — an observation which has passed without any 

 recognition. The following is my observation : — " This resemblance 



