98 ALBERT FRANCIS BLAKESLEE. 



EXPLANATION OF PLATES. 



All figures were outlined with the aid of a camera lucida. Those in outline were 

 taken from stained and mounted material. Those stippled show development in 

 living material from moist chamber cultures. Figs. 8-12, 18-24 and 31-32 were 

 viewed with a low power objective and were magnified by the use of increased 

 tube length or higher eye-pieces. Other figures represent high power drawings. 



PLATE I. 



FIGS. 1-7. Absidia spinosa. Consecutive stages in zygospore development 

 from living material. Only those outgrowths in median focus are represented. 

 Drawings were made at following hours: Fig. i at 4.15 P.M., Dec. 4; Fig. 2 at 

 4.52 P.M.; Fig. 3 at 5.50 P.M.; Fig. 4 at 7.10 P.M.; Fig. 5 at 12.30 A.M., Dec. 5; 

 Fig. 6 at 2.15 A.M.; Fig. 7 at 3.00 P.M. The dotted circle in Fig. 6 represents 

 the outline of a drop of fluid around the young zygote. 



FIGS. 8-10. "Imperfect hybridization" between Absidia spinosa (8) and 

 the (+) race of Absidia ccerulea (A(+)). Fig. 8 on right, typical conjugation of 

 Absidia spinosa; on left, "imperfect hybridization." Fig. 9 drawn at 8.30 A.M., 

 Sept. 23. Fig. 10 drawn at 4.00 P.M., Sept. 24. Note azygospore formed from 

 the male gamete of the $ hypha. 



FIGS, it AND 12. "Imperfect hybridization" between Zygorhynchus Moelleri 

 ( 8 ) and Mucor V. (+). Fig. n, male azygospore from 8 hypha. Fig. 12, three 

 "imperfect hybridizations." 



FIG. 13. Azygospores formed from male and female gametes of Zygorhynchus. 



FIGS. 14-17. "Imperfect hybridizations" between Mucor V. (+) and A. 

 spinosa ( ) Figs. 14-16, azygospores developed from male gametes of the Q . 

 Fig. 17, gametes on the $ . 



