ACTINOPHRTS SOL. 23 



instances in wliicli the plasma was crowded witli living- 

 green algal cells; these individuals he referred to a 

 separate species, A. pida, 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 



I 

 / 



^■Ssii 



T 



' I 



¥i(i. 182. — AcHiiophfys sol. Individual which had inyested a larg'e 

 diatom. (After Wallich.) 



l)y the pseudopodia elongating and Ijending 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 l)e 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" containing ingested food immersed 

 in a pale greyish-coloured liquid. 



Sometimes a gathering is found to contain numerous 

 small individuals measuring onl}^ 15 fx to 2-5 jx in 

 diameter ; these usually contain many small particles 



