484 MAECUS M. HAETOG. 



the isolated later arrivals. We may often see in the half- 

 emptied sporange a file of say eight or ten equidistant zoospores 

 going towards the opening ; the hinder ones move leisurely 

 enough, keeping their distance ; the front ones quicken up their 

 motion and lengthen their distance as they get to the mouth, 

 and leave it with a run, like a late arrival when he is stimulated 

 by coming in sight of the theatre. At length, when there are 

 but two or three left in the sporange, they may be seen to move 

 to and fro leisurely, as if careless of any goal, till when they 

 happen as it were to get towards the apex ; then they too quicken 

 speed and go out, but less fast than in the earlier stages of 

 emission, and so finally leave the sporange empty. Only when 

 the water is not well aerated a number of zoospores may remain 

 inside. 



We now turn to those that have left the sporange in 

 Achlya, grouped in a sphere outside. Each revolves on its 

 long axis for a short time, then goes to rest, rounds off and 

 becomes encysted in a cellulose wall, closely united with its 

 neighbours. Sometimes, however, a few zoospores of Achlya 

 may escape from the sphere and swim off a short distance to 

 turn on themselves for a short time (sometimes becoming 

 amoeboid), round off, and encyst quite isolated. As these 

 motions clearly indicated a motor organ, I used the usual reagent 

 for cilia and flagella, iodine solution, which at once demonstrated 

 the flagella in the moving zoospores, inside or outside the spo- 

 range, as seen by Cornu and denied by Biisgen and De Bary.^ 



' Cornu's words are most explicit. " Le trait d'union entre les Sapro- 

 let'uia et les Achlya a cependant ecliappe jusqu'ici a tous les botanistes. 



" Les zoospores sont de deux sortes, coinme chez les Saprolegaia 

 [italicised ia the original]. Les premieres, au lieu de se mouvoir pendant 

 plusieurs minutes ont juste assez d'agilite pour gagner I'ouverture du 

 sporange ; elles sont munies de deux cils anlerieures, visibles dans les condi- 

 tions favorables. Elles adherent les unes aux autres en general par le moyen 

 de ces cils. . . . Au bout de ce temps [three or four hours] elles presen- 

 tent, soit le premier mode de germination, qui consiste a s'allonger en 

 filaments, soit le deuxieme, et emettent alors des zoospores de deuxieme 

 nature" ('Monographic des Saprolegniees,' p. 11). 



In the face of this clear and detailed statement bj so trustworthy an iuves- 



