106 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Relationship between Cladophora and Rhizoclonium.* — A. Borzi 

 considers that many algae hitlierto considered as belonging to the 

 Confervaceae are not independent forms, but stages of development of 

 species of Cladophora. This applies especially to several species of 

 Bhizoclonium, which he has, in cultivation, developed into filaments 

 of Cladopliora ; thus confirming the previous hypothesis of Schmitz. 

 Gongrosira pygmcea he also shows to be a form of Cladophora fracta. 



The multinucleated condition of the cells, so common in the 

 Siphonocladiaceae, Borzi regards as simply the result of imperfect 

 septation. 



Classification of Confervoidese.t — A. Borzi proposes the new 

 family Chroolepidaceae, to include his new genus Leptosira (see p. 102) 

 along with Trentepohlia, Acrohlaste, Chlorotylium, Microthamnion, and 

 Pilinia ; which he separates from the Confervacese, and gives the 

 following classification of the Isogamous Confervoideee : — 



Segment-cells with several nuclei. 



Thallus unicellular. Fam. 1. Siphonacese. 



Thallus multicellular. Fam. 2. Siphonocladiacese. 



Segment-cells with a single nucleus. 



Thallus of a single lamella. Fam. 3. Ulvacese. 



Thallus filamentous. 



Chlorophyll parietal ; zoo- Fam. 4. UlotrichacesB 



sporangia not distinguish- (incl. ChEetophoracese). 



able from the vegetative 

 cells. 

 Chlorophyll diffuse ; zoospo- Fam. 5. Chroolepidacese. 



rangia distinguishable from 

 the vegetative cells. 



Action of Tannin on Fresh-water Algse.} — J- ^- Schnetzler had 

 previously demonstrated the presence of an appreciable amount of 

 tannin in fresh-water alg£e, Vaucheria, Spirogyra, Conferva, &c. If 

 the alcoholic solution of the chlorophyll of these algae is treated with 

 sulphate of sesquioxide of iron, an abundant blue precipitate takes 

 place. If the entire fresh vigorous algae are immersed in a solution 

 of this salt of iron, they remain green for a considerable time, the 

 cells becoming a dark blue only after the death of the protoplasm. 

 The cells of Spirogyra seem to display great variation in their 

 tenacity for life. In a green filament certain cells, either adjoining 

 or separated, may be seen to become dark blue under the influence of 

 the iron-salt. The position of these cells shows that their taking this 

 colour cannot be due to external causes, but to their individual 

 peculiarities, to the degree of resistance which the living protoplasm 

 ofiers to the action of the iron-salt. After a time, when the proto- 

 plasm of all the cells is dead, the whole filament is coloured dark 

 blue. Tannin appears therefore to be here an essential ingredient 

 of living protoplasm. 



* Loc. cit. t Loc. cit. 



t Bot. Centralbl., xvi. (1883) pp. 157-8. 



