AMONG SIMPLE SAKCODE OKGANISMS, 

 Fi?. 10. 



287 



Actino»phcerii;m Eichhornii. Optical section through a part of the margin. 

 m, endosarc ; r, ectosarc ; a a a, pseudopodia, the axis filament passing through 

 the ectosarc into the endosarc ; n n, nucleus with nucleolus ; /, an ingested 

 food-mass. (After Hertwig and Lesser.) 



The fusion of two or more fully developed individuals, as in 

 Actinophrjfs, lias also been frequently observed in ActinospTicerium. 



Actinophrys and ActinospTicerium had been united by Haeckel 

 into a small group, to vrhich he assigns the name of Heliozoa. 

 Since then, however, their structure has been found to be far more 

 widely represented than had been imagined by Haeckel ; and the 

 Heliozoa have received large additions from certain rhizopodal 

 forms occurring chiefly in fresh water. These have been mostly 

 referred by their discoverers to the Eadiolaria, which many of 

 them resemble in external form. Their affinities, however, are 

 undoubtedly with Actinophrys and Actinosphcerium, and their sys- 

 tematic place is among the Heliozoa. The establishment of this 

 group thus constitutes an important step in the systematic zoo- 

 logy of sarcodic organisms. 



We are indebted to several recent observers, and more especially 

 to Greeff". Archer, F. E. Schulze, Focke, and Hertwig and Lesser, 

 for a long series of interesting researches on these Eadiolaria-like 

 organisms of fresh water. The discovery of freshwater forms 

 resembling the true Eadiolaria, which have been hitherto known 



