"418 BIOLOGICAL STUDY OF TAP WATER. 



Other Chloropliyllaceous Algae present were Protococcus sp. ? 

 ChlorococcuB sp. ? diam, of cell itself being 0-0176 mm., and of 

 cell together with its hyaline coat 0-0264 mm. Ankistrodesmus 

 {Rhaphidiuwb) fcdcatus, Scenedesmus quadricauda, Pediastrum sp. ? 

 Pediastrum Boryanum. The forms included in this latter species 

 vary somewhat from the description given by Rabenhorst and Archer. 

 The coenobium is circular in outline, cells in a single stratum, 

 arranged in three rows round a central cell (1 + 4 + 10 + 15); 

 inner cells variable, 4-6 angled, concave at one side ; peripheral cells 

 convex on the inner side, on the outer side notched and tapering into 

 two long subulate points. Diam. of peripheral cells 0-0065 mm. 

 ( = about Tihns")- 



I have also seen another species of Pediastrum, which is not 

 described in any work to which I have had access. The cells are in 

 a single stratum, and in two rows round a central cell (1 + 6 + 12) \ 

 inner cells polyhedral, 4-6 angled ; peripheral cells pentagonal ; 

 ■external angle produced into a single process about as long as the 

 diameter of the cell. Diam. of coenobium 0-0434 mm. ( = 0-00173"), 

 and of peripheral cells 0-0124 mm. ( = 0-0005"). 



Spirogyra sp. ? Sterile joints 10 times as long as broad ; spiral 

 single with 4 turns; cell wall at each end produced. Diam. 0-0124 

 'mm. ( = 0-0005"). Fertile joints not observed. 



Phycochromaceae. 



Belonging to the Phycochroms there were a few forms observed, 

 viz. : — 



Gleocapsa sparsa, which is probably only a zooglaea stage of 

 Sirosiphon ; Merismopedia nova- (sp. ?) ; and at least two species of 

 Osoillaria, which have been referred to Os. nigra, Vouch, and Os. 

 ■chlorina, Kiltzing, the former being quite common during the month 

 •of March, more so probably than at any other time. 



SCHIZOPHYTAE. 



Under the name Schizophytes are included all the organisms com- 

 monly known as Bacteria, together with a few parallel green forms, 

 multiplying chiefly by transverse fission, though in some cases spores 

 are formed. These organisms at best have but a doubtful reputation ; 

 and if Intermittent and other malarial fevers, Anthrax, Diphtheria, 

 Septicaemia, Pyaemia, Tubercle, and other virulent contagious dis- 





