ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 273 



for tlie determination of species, and even in some cases of genera, 

 but not of the larger groups, since their formation probably depends 

 on external conditions. 



Hybridism in the Conjugatse.* — C. E. Bessey describes an 

 interesting case of hybridism between two species of Spirogyra, 

 S. majuscula and proteda. A perfect zygospore was found, resembling 

 most nearly those of the latter species. 



New Genera of Chroococcacese and Palmellacese.f — In an account 

 of the algae of Sweden, G. Lagerheim describes as many as sixty 

 species new to that country ; and gives also the following diagnosis 

 of new genera : — 



Gleochcete (Chroococcacese). Cellulae globosae vel eubovales, binse 

 vel quaternge in muco communi homogeneo vel indistinctissirae 

 lamelloso inclusae, utraque seto longissimo instructa. Cytioplasma 

 ferugineo-cserulea, subgranulosa. Divisio cellularutn in duas direc- 

 tiones. One species, G. Wittrochiana, possibly identical with Chceto- 

 coccus hjalinus Kiitz. 



Acanthococcus (Palmellaceae). Cellnla3 adultae globosae vel sub- 

 globosae, aculeis praeditse. Divisio succedanea, multitudo cellularum 

 filialium globosarum, non aculeatarum, in cellula matricali provenit, 

 quae, membrana cellulae matricalis in mucum conversa, liberae fiunt. 

 Cellulae perdurantes oleosae. Two species, one of them the Palmella 

 Mrta and Pleurococcus vestitus of Reinsch. 



Dactylothece (PalmellaceEe). Cellulae cylindricae vel oblongae, 

 rectae vel leviter curvatae, utroque fine rotundatae, singulae-quaternae in 

 familiis consociatae, tegumentis vesiculiformibus inclusae. Familiae 

 numerosae hoc modo formatae stratum viride uliginosum formant. 

 Divisio cellularum in unam directionem fit. Cytioplasma viridis. 

 Zoosporae ignot^. Analogous to Glceothece among Chroococcaceae. 

 One species, D. Braimii, in greenhouses. 



Also the subgenus Holopediiim : — Merismopedium familiis forma 

 irregulari e cellulis irregulariter dispositis compositis. Divisio 

 cellxtlarum irregularis. Includes the three species of Merismopedium, 

 irregulare, sahulicolum, and geminatum. 



Chroolepus nmbrinum. j — J. B. Schnetzler finds this alga, associ- 

 ated with a number of others, on the bark of the vine, forming 

 moniliform threads of globular cells about 30 /x in diameter. It also 

 occurs in similar localities imbedded in the thallus of a lichen 

 belonging to the genus Pyrenula. In this condition it forms fila- 

 ments composed of much smaller cells. When the licheu-thallus 

 decays, these cells escape, and, on multiplying, assume again the 

 normal size of those of the free form. 



Constant Production of Oxygen by the Action of Sunlight on 

 Protococcus pluvialis.§ — In the summer, Zygnema and Conferva may 



* Amer. Natural, xviii. (1884) pp. 67-8. 



t Oefvers. af Svenska Vetensk. Akad. Forhandl., 1883, pp. 37-78 (1 pi.). 

 X Bull. Soc. Vaud. Sci. Nat., six. (1883) pp. 53-4. 

 - § Cliem. News, xlviii. (1883) pp. 205-6. 



