28G H. MARSHALL WAED. 



In this quiescent condition it remained for some hours un- 

 changed^ excepting that an envelope was gradually formed on 

 its surface. At 2.o0 p.m. the contents of the little sphere came 

 out (c and d) as an amoeboid, naked mass, which gradually 

 acquired' a kidney-shape and a large vacuole, and developed 

 two lateral cilia ; these latter, as before, arose as two minute 

 knobbed processes, which slowly increased in length and began 

 to wave, causing the body of the zoospore to swing more and 

 more, and at length (about 3 p.m.) to move away. This par- 

 ticular specimen was then lost. But I observed another (/"to 

 i) for nearly an hour and a half; it was just coming to rest (g) 

 about 4 o'clock, and had commenced to germinate before 5 

 p.m., growing very rapidly {t) and then dying. In another 

 case (fig. 18) I followed the second more closely. It escaped 

 from the envelope {a, h) about 2.10 p.m., and swarmed as a 

 kidney-shaped spore (c) for nearly half an hour; it then lost its 

 cilia, writhed two or three times in an amoeboid manner [d), 

 and suddenly became rounded off (e) as a naked spore. This 

 was at 2.55 p.m. At 3.15 (/"jit began to germinate, by throw- 

 ing out a slender tube, which had reached a considerable 

 length by 4 o'clock (</), when the whole was dying. 



In the normal condition of affairs such a germinal tube 

 enters the body of the insect, and continues the life-cycle. In 

 some cultivations one often finds bright white clumps of ger- 

 minating zoospores (fig. 20) lying at the bottom of the water; 

 these result from numerous zoospores coming to rest about the 

 same time, falling quietly through the still water, and, again, 

 germinating almost simultaneously. 



There is little more to be said concerning these processes. 

 The zoosporangia of this Saprolegnia vary in shape 

 within wonderfully Avide limits ; some are almost as broad as 

 long, others nearly tubular, while pyriform, top-shaped, and 

 irregular specimens of all kinds occur. In cultivations, allowed 

 to starve from want of renewed water, &c., imperfect and dis- 

 torted sporangia reach a certain stage of development, and 

 then, acquiring very thick walls, remain in a resting con- 

 dition, springing into activity again when the conditions of the 



