A EEMAEKABLE MARINE ORGANISM. 447 



up, SO that by repetition of the process a large stratified mass is 

 formed in which the lower layers are composed almost entirely 

 of empty cellulose sheaths and the flocculent staining-material 

 (remains of zoogloea ?). 



I have not been able to demonstrate the existence of cocci 

 m the flocculent layers or network of Fontobolbos, though I 

 have detected occasional indications of their formation within 

 the sheaths ; and the fact that the outermost flocculent layer is 

 already present before the threads in the layer below it have 

 discharged their contents (PL 27. fig. 9) seems to indicate that 

 it cannot be entirely due to zoogloea formation. According to 

 Klein*, zoogloea masses always present themselves as uniformly 

 granular, the granules or micrococci being of the same size. 

 The darkly staining layers and network of TontoboJbos, on the 

 other hand, are by no means uniformly granular but rather 

 flocculent. They contain granules of various sizes, but com-^ 

 paratively few that are at all sharply defined. 



The Bacteria, such as Leptothrix and Crenothrix especially, 

 are well known to be very closely related to the blue-green 

 algae (CyanophycecB) t, and there are certain species of the latter 

 group which are also in some respects pretty closely comparable 

 with Pontobolbos. 



Such especially appears to be the case with the Oscillarian 

 Lyngbya (PJiormidium) membranacetmi, which forms firm, 

 leathery layers of a greenish-black or olive colour ; with threads 

 3-8 n thick, greenish or brownish, and delicate colou.rless sheaths. 

 The terminal cell is narrowed and often provided with fine cilia 

 at the apex. This species was placed by Kiitzing in the genus 

 Fhormidium, distinguished from Lyngbya by the fact that the 

 sheaths are grown together to form a firm, often laminated 

 structure. More recent authors, however, appear no longer to 

 keep the two genera apart J. This description also is certainly 

 very suggestive of Pontobolbos, though the threads are very 

 much thicker. I am not aware, however, that the darkly staining 

 layers and network have ever been seen in a Lyngbya or indeed any 

 Oscillarian. If the threads of Pontobolbos were really Lyngbya 



* ' Micro-Organisms and Disease,' p. 60. 



t Thus Le Maout and Decaisne include Bacteritim and Leftothrix, together 

 with Oscillatoria, Lyngbya, and others, in the one family Oscillatoriece. 



I Vide Eeinhold, "Die Cyanophyceen (Blautange) der Kieler Fohrde" 

 CSchrift. d. Nat. Vereins. fiir Schleswig-Holstein, Bd. viii. Heft 2, p. 173). 



