22 



THE AMERICAN MONTHLY 



[February, 



formation occurs in sterile plants ; 

 the granular cliloropliyll becomes 

 homogeneous, separates from adjoin- 

 ing cells, and forms sub-spherical 

 masses, as B C ; at the same time 

 the firm outer structure of the 

 cells, or filaments, changes to a soft, 

 colorless, gelatinous sheath, and 

 then gradually widens to an appear- 

 ance resembling D ; the sub-spher- 

 ical, green cells divide ; thus we 

 have, instead of the representation 

 of Conferva^ a typical Mormospora. 

 Mr. Cienkowski, of St. Petersburg, 

 observed a similar transformation 

 in species of JJlothrix, and infers 

 that all plants hitherto classified 

 under Ilormospora, are doubtful 

 species. "We have a number of 

 plants Avhich possess or assume the 

 generic character of this genus. 

 They are filamentous, and composed 

 of a series of cells surrounded by a 

 wide, gelatinous sheath, similar to 

 the sheath which encloses the 

 filaments of Hyalotheca, of Didy- 

 mopriura, and of young forms of 

 Bamhiisina. These are certainly 

 distinct forms. Hormiscia moni- 

 liformis^ Ktz., has a similar, though 

 closer sheath, but may be looked 

 upon with doubt. During the past 

 summer I found a plant of like 

 structure, purplish color, but much 

 thinner ; it suggested the name 

 Hormospora purjpurea; another one 

 received from Prof. Hobby, of 

 Iowa, I have temporarily named 

 Hormospora Hohhyi. These three 

 have a uniform character through- 

 out, and yet are so like the forms 

 of Conferva and Ulothrix approach- 

 ing decay that their specific identity 

 may be questioned. 



The study of living specimens of 

 these forms is recommended as 

 profitable work. 



To return to the fi^ures,^ G re- 

 presents Conferva fugacissima, 

 Roth., and is put in merely for an 

 illustration of variety; ZT is a 



fertile filament of Microspora vul- 

 garis, Thuret ; /is the same in a 

 transition state ; -/is more advanced, 

 and Austin older and so absolutely 

 distinct it could not be recognized. 

 If taken away from less developed 

 forms, it might pass for a good 

 form of Ulothrix I L is Conferva 

 ahreviata, Rabh., in its usual con- 

 dition ; M the same in a distinct 

 and new form ; the cytioderm 

 has become more gelatinous and 

 wider, the cell contents globose, 

 finely granular, and covered with 

 a very thin, scarely perceptible 

 envelope. At one end of the 

 filament, these cells are represented 

 divided ; JY shows them divided a 

 second time. The plant in this 

 stage of its life also resembles 

 Hormospora and would make a 

 good species. Passing through a 

 stage of dissolution, the cells con- 

 tinue to divide and redivide — early 

 habits cling to them even unto the 

 end. O YG^veQQni^ Conferva punc- 

 talis, Rabh., and P a form derived 

 from it, which would make a good 

 species of Qlomtila, Ktz. 



To identify fresh-water Algse, 

 repeated examinations should not 

 be considered needless. 



F. WOLLE. 



Preparation of Ranvier's 

 Picro-carmine. 



BY S. H. GAGE. 



The preparation of this excellent 

 staining agent is somewhat diflScult, 

 owing to the fact that the right pro- 

 portions of its ingredients and the 

 precise operations for its manu- 

 facture have not been definitely de- 

 termined. 



Ranvier's directions are, to add 

 an ammoniacal solution of carmine 

 to a saturated solution of picric acid, 

 until saturation. Four-filths of this 

 mixture is then evaporated in an 



