Species of Olpidiopsis, (Cor mi) Fischer . 237 
Fig. 18. Stage of developing sporangium showing the organization of regular vacuoles with 
diminished condition of the host protoplasm. 
Fig. 19. Swollen hypha of Saprolegnia containing discharged and undischarged sporangia of 
0 . vexans. The latter are in the resting condition. 
Fig. 20. A sporangium of O. vexans in an old culture, showing a peculiar coiling of the long 
exit tubes. 
Fig. 21. A slightly swollen hypha of Saprolegnia containing three empty sporangia and two 
mature oospores of O. vexans. 
Fig. 2 1 A. An oospore of 0 . Saprolegniae drawn to the same scale as Fig. 2r. 
Fig. 21 B. An oospore of 0 . luxurians drawn to the same scale as Figs. 21 and 21 A. 
Fig. 22. Portion of a sporangium of 0 . luxurians stained with Gram’s stain. Shows the 
presence of faintly stainable bodies in the vacuoles. 
Fig. 23. Large fat granule from a young sporangium. Much vacuolated. 
PLATE XXIV. 
Fig. 24. Young oogonium and attached antheridium of 0 . luxurians. 
Fig. 25. An older stage of the sexual organs of 0 . luxurians. Two young sporangia are present 
in the same hyphal swelling. 
Fig. 26. Young developing oogonium and two antheridia of O. vexans. 
Fig. 27. Nearly mature oospore of O. vexans showing large oil globules and slightly roughened 
wall. 
Fig. 28. Young oogonium and antheridium of 0 . luxurians slightly older than Fig. 25, which 
shows the developing spines and the large number of oil globules, also the granular protoplasm. 
Fig. 29. Same specimen as in Fig. 28, two hours later. Spines are mature and the antheridial 
contents is passing into the oogonium. 
Fig. 30. Mature oospore of 0 . luxurians bearing two empty antheridial cells. 
Fig. 31. Young uninucleated sporangium of 0 . vexans soon after the entrance of the zoospore 
into the host. 
Fig. 32. Binucleated sporangium of 0 . vexans. 
Fig. 33. Binucleated sporangium of 0 . vexans , showing the nuclei in the act of division. 
Fig. 34. Slightly older sporangium of 0 . vexans , showing its vacuolate character and the 
nuclei in division. 
Fig. 35. Mature zoospores at the time of discharge from the sporangium, showing well-marked 
vacuoles. 
Fig. 36. Sporangium of 0 . vexans , showing the peripheral arrangement of the protoplasm. 
Fig. 37. Portion of a developing sporangium of 0 . vexans. The large vacuoles are forming 
and the nuclei are undergoing the last division before zoospore formation. 
Fig. 38. A portion of a sporangium of 0 . vexans in the vacuolate stage following the condition 
shown in Fig. 37. Spore centres formed but not sharply marked off. Chromatin of the nuclei 
collected at the periphery. Fixed in weak chrom-acetic acid. 
Fig. 39. A portion of a sporangium of the same age as that shown in Fig. 38, fixed in weak 
Flemming’s solution. Segmentation of the contents into zoospores clearly visible. 
PLATE XXV. 
Fig. 40. Young oogonium and antheridium of 0 . vexans , showing the nuclei in a state of division. 
Both contain large vacuoles. Nuclei more or less irregularly distributed. No membranes apparent. 
Fig. 41. Shows the wall between the oogonium and antheridium gelatinizing to forma fertiliza- 
tion pore. 0 . vexans. 
Fig. 42. A later condition of Fig. 41. Nuclei of antheridium in division, while those of the 
oogonium are in the resting condition. 0 . vexans. 
Fig. 43* Sex organs of 0 . luxurians showing actual passage of male nuclei into the oogonium. 
Nuclei of the oogonium poorly stained. Gram stain. 
Fig. 44. Fertilized oospore of 0 . vexans. The nuclei, which are very small, are collected more 
or less in groups. Large granules, probably fatty in nature, scattered throughout the thin protoplasm. 
Fig. 45. A section of a mature oospore of 0 . luxurians , showing the thick endospore, peripheral 
layer of protoplasm containing the nuclei, the large central granules, and an oil globule. Nuclei 
very indistinct. 
