466 Smith . — - Cytological Studies in the Protococcales . I. 
After coming to rest the zoospore develops without cell division into 
the new plant, but the nuclei increase in number by simultaneous division as 
the cell enlarges. 
Bibliography. 
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vol. xxxi, 1910, p. 203. 
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DESCRIPTION OF FIGURES ON PLATE XL 
Illustrating Mr. G. Morgan Smith’s paper on Zoospore Formation in Characium Sieboldii. 
All the figures were drawn with the. aid of the Abbe camera lucida, the drawings being made 
at the level of the base of the microscope. Figs. 1 and 7 were drawn with the Leitz oil-immersion 
objective T V an d ocular 4 (magnification about 2,000 x); while in Figs. 2-6 and 8-12 the 
ocular 3 was used (magnification about 1,650 x ). Figs. 13-17 were drawn with the Zeiss 2 mm. 
objective, 1*40 N.A., and compens. oc. 18 (magnification about 3,800 x ). 
Fig. 1. Mature cell showing position of pyrenoids and nuclei. 
Fig. 2. Cell with simultaneous division of nuclei and the beginning of cleavage. 
Fig. 3. A stage at the beginning of longitudinal cleavage. 
Fig. 4. Showing the cleavage into several multinucleate masses. 
Fig. 5. After the cleavage into uninucleate masses. 
Fig. 6. Uninucleate masses partially rounded up to form zoospores. 
Fig. 7. Young zoospores nearly ready for liberation. 
Figs. 8-1 1. Stages in the development of the young colony. 
Fig. 12. A cell showing ‘stroma’ starch. 
Figs. 13-16. Stages in nuclear division. 
Fig. 17. Nearly mature zoospore. 
