ADDENDA. 



Since the paragraph (page 16), regarding the motion of granules 

 in the vacuoles of Closterium and other desmids, was put into print, 

 I observe a notice of a somewhal novel view of the phenomenon, in 

 the Journal of the Royal Microscopic Society of London, Feb. '84. 

 I transfer it as of interest, without comment. 



"The occurrence of crystals of calcium sulphate, endowed with 

 a peculiar " dancing " motion, has long been known in the terminal 

 vesicles of Closterium and in other desmids; the phenomenon has 

 now been carefully investigated by A. Fischer. Their chemical 

 constitution was clearly established by differenl tests. They are 

 always quite isolated from one another, and occur in all parts of 

 the cells, though in the greatest quantity in the terminal vesicles; 

 they are either carried along passively by the currents of proto- 

 plasm, or they 'swarm' in the space filled with cell-sap between 

 the cell-wall and the radiating chlorophyll-bodies; these vesicles 

 are not true vacuole-. Imt portions of cell-sap space. The crystals 

 are not formed, nor do they grow, in the vesicle, but reach it in a 

 mature condition from some other part of the cell, being formed 

 apparently in the furrow- between the bands of the chlorophyll- 

 bodies; from here they are carried to the terminal chambers by the 

 protoplasmic currents. 



Fisher found these crystals in all species of Closterium which he 

 examined; also in various species of Cosmarium (though indi- 

 viduals arc often entirely destitute of them), their form being the 

 same as in Closterium. They occur in Micrasterias } Ehiastrum, in 

 which genera also they are not invariable present, and always in 

 Pleurotaenium, Penium, and Tetmemoris, but were absent from all 

 the specimens examined of Staurastrum, Desmidium and Hyalotheea. 

 They appear to be entirely confined to the Desmidieae, other fresh- 

 water Algce containing calcium oxalate, especially species of Spir- 

 ogyra but not calcium sulphate." 



For details the original paper must be consulted in Pringsheim's 

 Jahrb. f. Wiss. Bot. XIV, (1883) pp. 133-184. 



(157) 



