AMO:^^G SIMPLE SAECODE ORGAJflSAfS. 



291 



Besides the truly naked Heliozoa, represented by Actinophrys , 

 CiliopJirys, and Actinosphaerium, a large number of others have 

 been discovered, which, as shown by Archer, are enveloped in a 

 soft outer investment, which he describes as an outer sarcode 

 zone, and which may be either entirely destitute of hard parts, 

 or which may have immersed in it hard skeletal parts, chiefly in 

 the form of spines or spicula. The chlorophyl and other coloured 

 granules which are frequently present in the inner body mass 

 are never developed in this outer zone ; and it is in the inner body 

 that the pseudopodia always have their origin, merely passing 

 through the outer zone on their way to the surrounding water. 

 Whether this zone, however, is to be regarded as a true sarcode 

 layer is -extremely doubtful. It is, at all events, quite distinct 

 from the proper ectosarc which it surrounds, and is probably only 

 an excretion from this, comparable to the gelatinous excretion 

 which is poured out on the surface of many of the lower Algse. 

 Hertwig and Lesser go so far as ta deny its existence, and refer 

 the appearance of an outer sarcode-like zone to an entanglement 

 of needles and spines, even in those cases where Archer refuses to 



Fis. 12. 



Hcferophrt/s &pinifera. c c, contractile vacuoles ; n, central dark body 

 (endosarc or nucleus). (After Hertwig and Lesser.) 



