198 ON THE SAPROLEGNIEiE. 



EXPLANATION OF PLATES XXXVIL and XXXVIII. 



Plate XXXVII. 



Fig.l. — Achlya : a, Oogonium; 6, Antlieridium. 



2. — a, Oospheres ; b, Antheridium ; c, Tubes of Antheridium. 

 3. — Oogonium containing protoplasm, with vacuoles. 

 4. — a, Oospheres ; b, Antheridium ; c, Tubes of Antheridium. 

 5 — 7. — Formation of Oospheres from toplasm. 

 8. — Antheridia (a) emptying themselves into (6) the Oospheres. 

 9. — Oogonium, with single Oospore and Antheridium. 

 10. — a, Oospores ; b, Antheridia. 



11. — Two sporangia of Achlya: A, one still closed ; B, with the zoo- 

 spores escaping ; a, zoospores just escaped and still in a state of 

 rest ; c, after commencing to swarm, having abandoned their 

 cell-walls (6). 

 12. — Oogonia and Antheridia of Achlya. Course of development 

 indicated by letters, A — E : a, Antheridium ; b, its tube, pene- 

 trating into the Oogonium. 



Plate XXXVIII. 



1. — Head of Smelt affected with Saprolegnia. 



2. — Scale of Salmon, with fungus in situ. 



3. — Monoblepharis ; general figure of plant. 



4. — Oogonium in process of formation. 



5. — a, Oogonium ; b, Papilla ; c, Antheridium. 



6. — a, Oogonium ; b, Papilla burst open ; c, Antheridium. 



7. — Antherozoids escaping and attaching to Oogonium. 



8. — Fecundated Oosphere, empty Antheridium. 



Parasites of Saprolegnia. 

 9. — Filament of Saprolegnia containing spores of Olpidiopsis. 

 10, — The same at a later stage and enlarged, showing absorption of 



protoplasm by the parasite. 

 11. — Filament, showing spores of Olpidiopsis^ in different stages of 

 growth : a, Emitting zoospores ; 6, Adult sporangium ; c, con* 

 taining vacuoles ; d^ more advanced spores. 



