694 SUMMARY OF CURRENT RESEARCHES RELATING TO 



however, being produced in alternate succession with the sexual 

 individuals. 



As regards the systematic position of the Floridefe, Schmitz con- 

 siders them as most nearly allied to the ColeochaBteaa among the 

 Chlorophycese. He dissents from Berthold's location of the Ban- 

 giacese * as constituting the lowest group of Florideae, pointing out 

 many important features in which they differ from the true Florideaa, 

 especially in the structure of the thallus, the position of the sexual 

 reproductive cells, the mode of impregnation, and the further develop- 

 ment of tbe fertilized oosphere. The arrangement of the families of 

 which the Florideae are themselves composed must remain at present 

 altogether uncertain. 



New Cyanophycea.'j' — Under the name Plaxonema E. Tangl 

 describes a filamentous alga with the habit of an Oscillatoria, pre- 

 senting the peculiarity of a disk-shaped chromatophore in the blueish- 

 green protoplasm. Under normal conditions reproduction takes place 

 by fragmentation by means of the formation of dead cells. Under 

 cultivation the filaments fii'st of all lose their motility and break up 

 into fragments of various lengths, preceded by the formation of narrow 

 interstices between the cells separated from the common envelope. 

 These fragments behave in two different ways. Some break up 

 directly into separate cells, while others develope into spherical 

 zoogloeas, which are either terminal or intercalary. The formation 

 of zoogloeas is followed by peculiar movements of the cells, which 

 separate and distribute themselves through the gelatinous mass, 

 caused by tensions of the common envelope resulting from the escape 

 of gelatine from the contents of the cells as an excretory product. 

 The zoogloea cells thus isolated have a cylindrical form with flattened 

 ends ; no further development was observed. They may be regarded 

 as the form of development of the alga described by Zopf as belonging 

 to the ChroococcaccEe group. 



Organic Bodies in the Thermal Waters of the Pyrenees. | — 

 N. Joly has determined that the so-called " sulfuraire de Fontan " of 

 the sulphurous waters of the Pyrenees is not, as was stated by Agardh, 

 a conferva, but a true Oscillatoria, to which he gives the name 0. vitrea 

 n. sp., endowed with the usual motility of the genus. 



Fossil Confervites.§ — M. Staub describes all the known species of 

 this group of fossil algaB, which he estimates at nineteen, including one 

 described for the first time. He considers that they became differen- 

 tiated from the large group of Chondrites, which died out in the 

 Tertiary. These algae have great stratigraphical importance in the 

 formation of rocks, from the great quantity of carbonic acid which 

 they removed from sea-water, thus bringing about the precipitation of 

 calcium carbonate. 



* See this Journal, ayite, p. 408. 



t K. Akad. Wiss. Wien, May -Itb, 1883. See Bot. Centralbl., xiv. (1883) 

 p. 285. 



X Mem. Acad. Sci. Toulouse, iv. (1883) pp. 11.5-35 (1 pi.). 



§ SB. Ungar. Geol. Gesellsch., xiii (1883) pp. 71-2. See Bot. Centralbl., xiv. 

 (1883) p. 303. 



