8 THE SAPROLEGNIACEAE 



Saprolegnia aslerophora deBary ('60). In plate 20, fig. 25, deBary 

 shows a partly emptied sporangium, the remaining spores sprouting 

 into tubes. 



Saprolegnia ferax (Gruith.) Thuret ('50). In plate 22, fig. 8, Thuret 

 shows an unopened sporangium with the spores sprouting in posi- 

 tion. This is a good example of the Aplanes method. In this 

 species Pringsheim ('73) gives an interesting case (fig. 12, plate 

 21) of the contents of an egg turning immediately into a sporangium 

 the spores being retained and sprouting in position. In figs. la, b, 

 c, plate 20, he shows spores that had been retained in a partly dis- 

 charged sporangium. These had sprouted in position to short tubes 

 which became sporangia and discharged small spores. 



In the case of a parasite on fish that he considers Saprolegnia 

 ferax, Smith ('78) gives a figure showing spores sprouting inside 

 the sporangium at one end while others are swimming out at the 

 other. Such a combination is probably fanciful. 



Saprolegnia monoica Pringsheim: Huxley ('82) describes the regular 

 occurrence towards the end of active growth of sporangia of the 

 Aplanes type. He calls them, improperly, "dictiosporangia. " In 

 this plant, which was a parasite on salmon, it is noteworthy that 

 Huxley found no motion in the spores but only a passive drifting 

 about when discharged. In a similar (probably the same) plant, 

 found as a parasite on fish, Unger ('44) gives a figure (fig. 11, plate 

 i) showing a few spores left in the sporangium and sprouting there 

 into long tubes. In this parasite he records the spores as swimming 

 on leaving the sporangium, not floating away as in Huxley's plant. 



Saprolegnia torulosa deBary: Lechmere ('10) illustrates in fig. 33, plate 

 2, a sporangium with spores sprouting after the manner of Aplanes. 

 He later gives ('11, fig. 2) another example. In his first paper he 

 shows that the second swimming stage may be suppressed. DeBary 

 ('84, p. 117) says that the second swimming stage may be omitted 

 in any species of Saprolegnia, and this we can confirm for the species 

 studied. 



Saprolegnia Jurcata Maurizio ('99). The spores are frequently retained 

 and sprout as in Aplanes. 



Saprolegnia sp.?: Pringsheim ('60). In plate 22, fig. 9, is shown a 

 sporangium emptying as in Dictyuchus. It is attached to a hypha 

 which also bears a sporangium of the normal Saprolegnia type. 

 Miss Collins ('20, figs. 3-1 1) also illustrates sporangia of both the 

 Dictyuchus and Aplanes types, or the two combined, in a sterile 

 species of Saprolegnia. 



