4 
Keene—Studies in Zygospore Formation. 1219 
EXPLANATION OF FIGUEES IN PLATES. 
All figures were drawn with the aid of the camera lueida and with the 
Zeiss apochromatic objectives and compensating oculars. Figures 8a; 9 a, b, c; 
10 a, b; 11a, b, c, d, e; 12 a, b; 14 a, b, c; 17 a, b, were drawn with objective 
1.5 mm. and ocular 12. Figure 8 was drawn with objective 1.5 mm. and 
ocular 8. Objective 16 mm. and ocular 12 were used with the remaining 
figures.., j 
Plate I. 
Figs 1 and 2. Young gametophores of plus and minus strains showing 
lobing and interlocking. 
Fig. 3. Young gametophores showing elongation of terminal portions. It 
is at this stage that the gametophores appear as erect yellow 
columns. 
Fig. 4. Enlargement of gametophores. 
Fig. 5. Formation of the delimiting walls. 
Fig. 6. Showing the origin of the spine-like appendages. 
Fig. 7. Mature zygospore with blackened wall and invested with appen¬ 
dages. 
Plate II. 
Fig. 8. Germinating spore of plus strain. 
Fig. 8a. Nuclei from germinating spore under higher magnification. 
Fig. 9. Section through progametes prior to septation or resorption. 
Figs. 9a and b. Nuclei from respective progametes. These may illus¬ 
trate phases of nuclear divisions. 
Fig. 9c. Crystalloids. 
Fig. 10. Young conjugating branches at the time of resorption of the 
separating wall. 
Figs. 10a and b. Nuclei from respective suspensors. 
Fig. 11. Young zygospore, showing characteristic grouping of the nuclei 
following fusion of the protoplasmic masses. 
Fig. 11a and b. Nuclei of the suspensors at time of formation of ap¬ 
pendages. 
