458 Miss H. Chick. On a Unicellular Green Alga, [Feb. 28, 



" A Study of a Unicellular Green Alga, occurring in Polluted 

 Water, with especial Reference to its Nitrogenous Meta- 

 bolism." By Harriette Chick. Communicated by Professor 

 Hubert Boyce, F.B.S. Eeceived February 28, — Eead March 

 12, 1903. 



(From the Thompson Yates Laboratories, University College, Liverpool.) 



[Plate 8]. 



A small, unicellular, green alga was noticed to be frequently present 

 in sewage, and sewage materials, when these had been kept for some 

 time. The same alga was also found to have seeded itself in dilute 

 ammoniacal solutions. This somewhat peculiar habitat seemed to 

 promise that something of interest might repay a study of the 

 physiology of the plant. On examination, under the microscope, it 

 was found to be an extremely small, unicellular, non-motile alga, with 

 a well-defined chromatophore, which latter contained a distinct 

 pyrenoicl. The general characteristics of the alga pointed to its being 

 closely allied to CMorella (Beyerinck),* and I have provisionally placed 

 it in that genus. CMorella vulgaris was originally described by 

 Beyerinck as possessing either no pyrenoid, or an insignificant one ; 

 Chodat,! on the other hand, has described the species as having 

 generally a pyrenoid, and has figured it accordingly. In a culture of 

 C. vulgaris, obtained from Krai, I have been unable to detect a pyrenoid, 

 and, since the alga here treated of possesses a very conspicuous one in 

 its chloroplast, I have ventured to attach a new specific name, and to 

 call the organism CMorella pyrenozdosa. Though in the higher forms, 

 such variation in cytological character between the species of a genus 

 is practically unknown, yet the same difference occurs between different 

 species of Sticlwcoccus,\ of Baphidium,§ and of Pleurococcus,\\ all genera 

 of unicellular green algse, showing very simple cell structure, and 

 more or less nearly allied to CMorella. 



The peculiar natural habitat of the plant, and its appearance in 

 ammoniacal solutions alluded to above, both pointed to a preference 

 for ammonia in its nutritive fluid. In fact, in one instance, this alga 

 was found to have grown in a dilute solution of ammonium chloride, and 

 it was thought worth while to make an estimation of the ammonia. 

 This was done by directly Nesslerising, and it was found that the 

 ammonia had disappeared. By distilling the solution with alkali, 

 however, the ammonia was obtained in a roughly quantitative yield. 



* ' Bot. Zeit.,' 1890, p. 730. 



t ' Beitrage z. Xryptogamenflora d. Schweiz.' 



X Matruchot andMolliard, 'Rev. Gen. de Bot./ vol. 13, 1902 (May). 

 § Chodat, ' Mem. de l'Herb. Boiss.,' 1900, No. 17. 



|| Snow, 'Annals of Botany,' 1899; Chodat, < Bull, de l'Herb. Boiss.,' 1894. 



