EXPLANATION OF THE PLATES. 259 



Fig. 15. Cosmarium Broomei, Tim. Front view, magnified 460 dianTeters. 

 Fig. 16. Cosmarium commissurale, Breb. Front view, magnified 750 diameters. 

 . Fig. IT. XantUdium armatum, Breb. Front view, magnified 260 diameters. 



PLATE XIV. 



Fig. 1. A sterile cell of Bhynchonema elongatum, Wood, magnified 450 diameters. 

 Fig. 1 a. Portion of a filament containing a fertile cell, with the spore nearly matured, amplified 

 450 diameters. 



Fig. 2. A filament of Shynchonema pulchellum, Wood, containing both fertile and sterile cells, 

 magnified 260 diameters. 



Fig. 3. The ripened spore of Spirogyra protecta, Wood, magnified 450 diameters. 



Fig. 3 a. Outline of conjugating filaments, and figure of a sterile filament, enlarged 250 diameters. 



Fig. 4. Sterile cells of Spirogyra longata (Vauch.), magnified 250 diameters. 

 Fig. 4 a. Fertile filaments, magnified 260 diameters. 



Fig. 5. . A filament of Aphanocheete repens,W ood, which has lost its cilia, magnified 460 diameters. 



Fig. 6. A fertile branch of Draparnaldia Billingsii, Wood, showing the chains of spores, mag- 

 nified 460 diameters. 



PLATE XV. 



Fig. 1. Portion of a filament of Spirogyra majuncula, Ktz., containing cells with mature spores 

 and others just commencing the process of conjugation. 



Fig. 2. A portion of a sterile filament of Spirogyra diluta, Wood, magnified 125 diameters, also 

 the outline of apair of conjugating filaments of the same amplification. 



Fig. 2 b. Conjugating filaments of Spirogyra diluta, Wood, magnified 125 diameters. 



Fig. 3 a. Portion of a sterile filament of Spirogyra setiformis (Both) Ktz., magnified 125 

 diameters. 



Fig. 3 b. Conjugating filaments of the same species, similarly amplified. 



Fig. 4 a. Cells of Spirogyra crassa, Ktz., preparing for conjugation. 



Fig. 4 c. Conjugating cells of the same plant in the first stage of union. 



Fig. 4 b. Conjugating cells containing nearly matured zygospores, enlarged 125 diameters. 



Fig. 5. Filaments of Mesocarpus scalaris, Hassall, commencing the process of conjugation, mag- 

 nified 125 diameters. 



Fig. 6. Sterile cells of Spirogyra insignis (Hassall) Ktz. 

 Fig. 6 6. Conjugating filaments of the same species. 



Fig. t. Conjugating filaments of Spirogyra parvispora, Wood, containing nearly matured 

 spores, magnified 125 diameters. 



Fig. 8. Portion of an ordinary sterile filament of Zygnema insigne (Hassall) Ktz. 



Fig. 8 a. Fertile filaments of the same, magnified 250 diameters. 



Fig. 8 b. Sterile filament in which multiplication of the species is taking place by the separation 

 of the cells, magnified 260 diameters. 



PLATE XVI. 



Fig. 1 a. Cells of Sirogonium. retroversum, Wood, just commencing the process of conjugation. 



Fig. 1 b. Sterile cells. 



Figs. 1 (Z and 1 e. Outlines of fertile cells; all of these figures are magnified 260 diameters. 



