89 



great want existing at the present day in the systematical defi- 

 nition of this genus and its species; for the most opposite things 

 have been described under the name Oscillatorice, and again 

 frequently the most similar forms have been enumerated as 

 distinct species. When one has observed for years the growth 

 of the Oscillatoriae daily in one's study, and noticed the mani- 

 fold changes of form in one species, it is really almost impos- 

 sible to conceive how travellers venture, during a short stay at 

 Karlsbad, to describe twenty, thirty, and even more new species 

 of this genus, a case which really occurred recently. 



M. Schwabe has limited his observations only to some few 

 of these plants of the sources of Karlsbad, and he has there- 

 fore succeeded in observing something useful respecting their 

 structure and propagation. The separation of the genus 

 Mastigonema from Oscillatoria cannot however be adopted ; 

 for the very plant belonging to it, is to be regarded as the 

 representative of the true Oscillatorice. It is interesting to 

 see that the sporangia or spore-threads of Nostoc anisococ- 

 cum, Spr., have been described and figured as four distinct 

 species of Spharozyga,', these supposed species of Sphcerozyga 

 stand in the same relation to the Nostoc as the Oscillatoria 

 Flos agues to our common small Nostoc. The complete history 

 of the development of the Alga, which M. Schwabe has figured 

 and described as Fischera thermalis, is of great interest ; this 

 probably is presented to us by the same M. Fischer to whom 

 natural history is indebted for one of the most interesting 

 discoveries of recent times*. 



M. Morrenf gives, with an accurate description of the struc- 

 ture of Conferva dissiliens, his views on the various generative 

 functions which are said to belong to this plant. He says that 

 the cells of this Conferva contain an almost homogeneous mass, 

 an endochrome, in which some distinct globules occur which 

 are converted into transparent vesicles yellower than the rest 

 of the mass, and exhibiting in their interior dark spots of a 

 brown or red colour. These larger globules which occur in 

 all true Conferva and have hitherto been regarded as similar 

 to the cellular sap-globules in other plants, are considered by 



* The discovery here alluded to is probably that of the shields of some 

 Infusoria being composed of silex. W. F. 



t Bulletin de 1'Acad. de Bruxelllcs, 1837, p. 303. 



