ALGOLOGICAL NOTES. 13 



Explanation of the Plate. 



All the figures were drawn to scale by means of Abbe's drawing- 

 apparatus (from Zeiss). 



The original figures to the Chapters III and IV were coloured, but the 

 reproduction in colours is at present very expensive, so that they were 

 printed in black only. 



The microscope used was the I B of Zeiss with the objectives DD and 

 3 mm. apochromate (dry system 0,95 N. A.) in connection with the eye 

 pieces 2 and 4, and the compensating oculars 6 and 12. 



The magnification of the figures are the following: 



Fig 1. 490 diameters, (DD X 4). 



Figs. 17, 21 and 22. 585 di'imeters. (3 mm. X comp. 6). 



Figs. 15 and 16. 610 diameters, (E X comp. 12 on a special microscope). 



Figs 2-14 and 18-20. 790 diametres, (DD X comp. 12). 



Fig. 23. 1140 diameters, (3 mm. X comp. 12). 



Fig. 1 Stigeoclonium tenue (Ag.) Kuetz., branch of a normal Individuum. 



Fig. 2. Empty cells. 



Fig. 3. Cells with escaping zoögonidium. 



Fig. 4. Zoögonidium. 



Figs. 5 — 14. Various stages in the development of the zoögonidia into 

 new plants. 



Figs. 15 — 16. Pediastrum-co\onies with aplanospores (N. Wille delin.) 



Fig. 17. Pediastrum-colony germinated from the aplanospores. 



Fig 18. Pediastrum-colony with aplanospores, showing the structures of 

 cell-walls. (The contents are shown only in a single cell.) 



Fig. 19 Staurastrum Sonthalianum Turner, from North Australia, verti- 

 cal view. 



Fig. 20. Staurastrutn pinnatum Turner, from North Australia, vertical 

 view. 



Fig. 21. Crucigenia irregularis Wille, from Finmark plankton, young 

 colony, irregularly developed as usual. 



