1889.] NEW-YORK MICROSCOPICAL SOCIETY. 33 



Under certain conditions, this branched form of bacillated lep- 

 tothrix may develop largely, and it tends strongly to gelatinize, 

 with a condensation of the jelly-coat into one or even two suc- 

 cessive outer sheaths. In these, a breaking up into long strep- 

 tococci-chains commonly occurs, which, by separation at the 

 anterior end, project from the filament in gracefully drooping 

 branches and finally become broken off. The branched lepto- 

 thrix, in other cases, produces small elliptical sporangia, con- 

 taining fine micrococci, which, after separation from the filament, 

 burst by gelatinization and form minute zoogloea-masses, full of 

 sprouting cocci. These may rise to the surface of the water and 

 create sometimes a blue metallic pellicle, sometimes a dry 

 mycoderm, made up of clusters of immobile bacilli, sprouting 

 cocci, leptothrix passing into chains of bacilli by fission, etc. 

 But, in other cases, they become saprophytic, attach themselves 

 to dying water-plants, and develop masses of colorless zoogloea, 

 sometimes several decimeters in length and with corresponding 

 thickness, full of clusters of bacilli or of mycelial filaments. 



With these, the special reproductive condition of the plant 

 begins, these filaments being invariably sheathed, articulated, 

 irregular in course, branched largely at right angles, and soon 

 putting forth delicate apple-shaped sporangia. From the arthro- 

 spores of the original leptothrix, also, similar articulated fila- 

 ments are generated through an interesting series of products of 

 segmentation and sprouting. These also gelatinize, first, by a 

 coating of irregular granules of jelly or lines of micrococci, some 

 of which occasionally diverge in streptococci-chains, and, finally, 

 by a dense coat which may itself become invested by an exterior 

 sheath. The protoplasm within the cells becomes condensed in 

 cylinders, irregular balls and granules, equal-sized cocci (sub- 

 dividing in fours), and often arthrospores, as in the leptothrix. 

 Where the terminations of two short branches, projecting at 

 right angles from neighboring filaments, happen to come in 

 contact, union of the branches takes place, and an arthrospore 

 may be formed at the point of contact. Exterior or exospores 

 are also abundantly formed along the filaments, sessile, on short 

 pedicels, or at the termination of filaments. 



In actively growing filaments, especially in water poor in iron, 

 chlamydospores are also sometimes formed in abundance, single, 

 or in series of two, three or more, and also on the end of short 



