ACTlXorilUYS SOL. 23 



instances in which the plasma was crowded with living- 

 green algal cells; these individuals he referred to a 

 separate species, A. picta, but we follow Penard in 

 considering this a synonym. 



The contractile vesicle is unusually large and 

 prominent, discharging at intervals of about one to 

 two minutes ; occasionally two or rarely three of these 

 may be present. 



The movements of the animal are normally very 

 slow, in fact it usually remains motionless, but on 

 occasion it can progress by a rolling motion set up 



FIG. 182. Actinophrys sol. Individual which had ingested a large 

 diatom. (After Wallich.) 







by the pseudopodia elongating and bending towards 

 a supporting surface to which the foremost ones 

 adhere and pull the organism forwards. 



The appearance of A. sol varies greatly, for although 

 the plasma itself is transparent and colourless, contain- 

 ing normally numerous vacuoles, it may be so loaded 

 with food particles and other matter that it becomes 

 quite opaque; the large vacuoles are also often absent, 

 their place being sometimes taken by one or more 

 "food vacuoles' 1 containing 1 invested food immersed 



o O 



in a pale greyish-coloured liquid. 



Sometimes a gathering is found to contain numerous 

 small individuals measuring only 15 /x to 25 ^ in 

 diameter ; these usually contain many small particles 



