652 Trow. — The Karyology of Saprolegnict . 
nucleus. One antheridium is drawn. Its fertilization-tube which is already 
almost in contact with an oosphere contains two male gameto-nuclei. x 610. 
Fig. 18. Section of an oogonium and two antheridia showing fully developed 
fertilization-tubes and two newly formed oospores, x 610. 
Fig. 19. Section of an older oogonium showing the pair of gameto-nuclei in the 
oospores still unfused but decidedly larger, x 610. 
S. Thureti , De Bary. Typical apogamy. 
(Possibly apogamous oogonia of S. mixta , De Bary.) 
Fig. 20. Section of an oogonium with uninucleate oospores. The nuclei are still 
small, x 660. 
Fig. 21. Section of an older oogonium with uninucleate oospores. The nuclei 
have increased greatly in size and have the same appearance as those about to 
undergo the reducing division except that the chromosome is much smaller, 
x 660. 
S. mixta , De Bary. (Intermediate condition with respect to apogamy.) 
Fig. 22. Section of an oogonium with oospores. One oospore is distinctly 
binucleate. The one to the right beneath had a second nucleus in another section. 
All the other oospores in the oogonium had certainly one nucleus, and some of 
them might possibly have had two. x 660. 
S. dioica , De Bary. Maturation of the oospores. 
Fig. 23. a , b , c, d, and e. Oospores in successive stages of development. The 
large deeply stained granules around the nucleus in e are developed from the 
smaller ones seen in b. x 610. 
S. Thureti , De Bary. Germination of the oospores. 
Fig. 24. Two uninucleate oospores. XH50. 
Fig. 25. A uninucleate and binucleate oospore. The separation of the nuclei 
in the latter is just completed. The indentation in the wall is the result of the 
method of preparation and is rather exceptional, x 1 150. 
Fig. 26. a and b. Successive sections of an oospore with 5 nuclei, x 1150. 
Fig. 27. a and b. Successive sections of an oospore with 6 nuclei. XI150. 
Fig. 28. a, b, c, and d. Successive sections of an oospore with 8 nuclei, in which 
the zoospore-rudiments have already commenced to form, x 1150. 
Fig. 29. One section out of four, of an oospore in which eleven zoospores had 
just been formed, x 1 150. 
Fig. 30. Section of a germinating oospore which contained altogether 12 nuclei, 
and has developed a germ-tube with a view to the formation of a normal sporan- 
gium. x 1 1 50. 
Fig. 31. Tangential section of a chlamydospore of S. mixta, x 1150. 
Fig. 32. Tangential section of an oogonium of S. dioica showing pseudo-karyo- 
kinetic figures. The figures are due to imperfect preparations of nuclei in the 
process of undergoing the reducing divisions. x6io. 
