18 



BRITISH FRKSIIWATEK IIHI.IOZOA. 



Wallicli (ISfilj) records an individual found at 

 Hampstead, London, 500 /a in diameter, spherical in 

 shape and restino- attached hj the extremities of its 

 pseudopodia to the sides of a glass vessel. 



The nuclei lia\'e a tendency to increase in size as 

 the individual g-rtiws ; in a specimen from Hampshire 

 measuring 550 jj. in diameter many of the nuclei were 

 25/xin diameter, but as it was obsei'ved under a cover- 



^ Prt^i\^ 





Fto. 181. — Actinos2>h:>'rriiiii. rirhhornii. A small animal captured by 

 the pseudopodia is srcn at m. iu process of ingestion. Other 

 organisms are enclosed in food-vacuoles in the endoplasm. c.v. 

 Contractile vesicles. Tlie figure on the riglit sliows the depression 

 left on the collapse of a contractile vesicle. (After Wallich.) 



glass its normal s|)lierical diameter might have l^een 

 less than tins. 



The number of nuclei varies greatly, but increases 

 with the size of the individual; th(( numbers visible in 

 a living specimen, however, are many fewer than 

 those that may be recognised if it be stained and com- 

 pressed under a cover-glass, liy wliicli means from one 

 to three hundred nuclei may be found, according to 

 the size of the specimen. 



