THE MYCETOZOA 



which thus enters the swarm -cell or zoospore stage swims free 

 in the water with a peculiar dancing movement produced by the 

 lashing of the flagellum. In this movement it rotates about its own 

 axis, and also moves as though over the surface of a cone, the apex of 

 which is situated at the posterior end of the zoospore (de Bary). 

 It is of an elongated pyriform shape, the narrow ("anterior") end 

 being continued into the flagellum, which is about half to two- 

 thirds the length of the body. The thicker (" posterior ") end may 

 be evenly rounded, and is then curled somewhat to the side, but 

 is often extended in short pointed pseudopodia (Fig. 2, a). The 

 protoplasm of the anterior part is hyaline, and a layer of hyaline 

 protoplasm invests the rest of the body, the interior of which is 

 granular. The nucleus, with its contained nucleolus, lies in front, 

 at the base of the flagellum, and the contractile vacuole at the 

 posterior end. Non-contractile vacuoles (some of which at least 

 may be food- vacuoles) are also present in the granular protoplasm. 

 The particles of the latter exhibit a change of position within the 

 body, which in the large swarm-cells of Amaurochaete atra recalls the 

 streaming movement characteristic of the plasmodia of the later stage. 



Instead of swimming free, the swarm -cells may temporarily 

 assume an attached creeping mode of progression, in which the 

 body is elongated, and the flagellum, ex- 

 tended in front, turns from side to side 

 with movements which appear to be ex- 

 ploratory in purpose. Sometimes the body 

 is contracted and sends out pseudopodia 

 from all parts of the periphery (Fig. 4, c). 



Bacteria abound in the wet places among 

 decaying vegetable matter, in which the 

 spores hatch. These are captured by the 

 zoospores by means of the pseudopodia ex- 

 tended from their posterior ends and drawn 



into the body, where they are digested in zoospore of sttmonitis frsca, 

 vacuoles (Fig. 2) (15). De Bary, to whom ^"iJiJSETS^ 1 



(After A. 



this mode of obtaining; food by the zoospores x soo. in a, it is captured by 



i /o AKn\ ii ^1 one of the pseudopodia at the 



Was unknown, States (8, p. 452) that their hind end- in c, it is enclosed 



nourishment is exclusively saprophytic at & 



this Stage. It is impossible to deny that anterior vacuole. 

 , i . i ..L Lister, 15.) 



it may be in part saprophytic, and it 



appears very probable that it is both holozoic and saprophytic. 



The swarm -cells multiply by division. In this process the 

 flagellum is withdrawn, the contractile vacuole disappears, and the 

 body assumes a rounded form. The nucleus, passing to the centre, 

 divides by karyokinesis (Fig. 3), and as the daughter nuclei resulting 

 from this division separate the protoplasm becomes constricted, and 

 division occurs in a plane transverse to the axis of division of the 



