INVEKTEBRATAj CRYPTOGAMIA, MICROSCOPY, ETC. 1001 



that the former remove from the nutrient fluid the substances which 

 serve for the nutrition of the latter. On fully developed torula-cells 

 they appear to have no injurious influence. 



New Microscopic Schizomycetes.* — V. A. Poulsen describes an 

 organism discovered by him belonging to the family Sarcinepe of 

 Schizomycetes, which he treats as a new genus and species under the 

 name Sarcinoglobulus pundum. It diflers from the genus Sarcina in 

 its spherical form and numerous cells. It occurs in sea-slime from 

 which sulphuretted hydrogen is given off. In similar situations he 

 found also a new species of Sarcina, S. lUoralis. 



Chlami/domonas hi/alina Cohn is also described again in detail, 

 and the old name C. uva restored. 



Social Bacteria. f — M. P. Van Tieghem remarks that in the 

 family of Bacteriacefe, the cells, whatever their form, spherical, 

 cylindrical, or spiral, are disposed in a variety of ways. Sometimes 

 they are arranged in a linear series, in the order in which they have 

 inci'eased or divided, so as to form long threads of beads [Micrococcus 

 urece, bomhicis, &c.), or cylindrical (Bacillas anthracis, the young state 

 of B. amijlobacter, &c.) or spiral filaments (Spirochiete), This is the 

 typical disposition, and is sometimes modified by the formation of a 

 gelatinous sheath either around the whole mass of cells ( Mi/conostoc), 

 or each separate cell [Leuconostoc) ; but this does not affect the 

 arrangement of the cells in a linear series, which is often contorted 

 and knotted on itself. 



Sometimes, on the contrary, the cells separate immediately after 

 segmentation, without preserving any mutual relation as to direction. 

 Then they either disperse in the surrounding medium without main- 

 taining any connection, or they secrete a gelatinous substance which 

 keeps them united in more or less considerable masses altogether 

 indeterminate in form (several species of Micrococcus, Bacterium, Sec). 



This permanent association in a linear series, and tliis immediate 

 dissociation into separate cells, present various connecting links, 

 which render the chai'acters diflicult and doubtful of applicati(jn in 

 the definition of genera and species. This does not appear to be the 

 case with a third mode of existence, which the author terms social 

 (agrctjre). 



Under these conditions the cells, spherical or rod-shaped, become 

 completely dissociated immediately after the division by which tliey 

 have been formed, turn and glide one over another, and remain in 

 intimate contact, cemented together apparently by a gelatinous 

 substance. Starting from a spore or primitive cell, there is thus 

 gradually developed a compact mass, with more or less sharj) out- 

 lino, which soon assumes a definite form, spherical, oval, or cul)ical, 

 and which increases by repeated and simultaneous bipartition of tlic 

 cells of which it is composed. When it has attained a curtain 

 dimension, it divides into two equal halves, which so^iarato slightly, 



♦ PouUeii, V. A., ' Ucbcr ciiiigo niikroskopisclio rilauzouorganisuicu.' !Soc 

 ' Bot. Zfit.,' xxxviii. (lst<(i) p. 50J. 



t 'Bull. S.c. But. Fniucc.'sxvii. (IS8U) pp. 118-1.k!. 



