THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



Vol. I. 



New York, March, 1880. 



No. 3. 



Notes on Actiiiosphaerium 

 Eichhornii. 



BY HERMANN C. EVART8, M.D. 



On looking over a gathering 

 from a stream in the neighbor- 

 hood of Philadelphia, about two 

 weeks after it had been collected, I 

 observed several beautiful and well 

 developed specimens of the above 

 mentioned Rhizopod. Not one spe- 

 cimen was discovered in the jar 



Fig. II. 



Actinospharium Eichhornii (Pseudopodia 

 extended), 



previous to this time. Probably 

 there are no Protozoa, in which the 

 functions of prehension, digestion 

 and assimilation of food are to be 

 more easily studied than in Acti- 

 n^spJuBrium and Actinophrys Sol. 

 but more especially the former, 

 owing to its greater size. Actinos- 

 phwnum presents much similarity 

 in structure and habits to Actino- 

 phrys^ and indeed, for a long time 



they were regarded as identical, 

 Kolliker designating the two ani- 

 mals by the same name {Actino- 

 phrys sol). 



In 1857, Stein proposed the se- 

 cond genus, Actinosphceriuin. The 

 body-substance of this animal is 

 distinctly diiferentiated into me- 

 dullary, and cortical regions, or in 

 other words, into endosarc, and 

 ectosarc. The ectosarc is composed 

 of sarcode arranged in the form of 

 large vacuoles, somewhat radiately 

 disposed ; it is from these that the 

 sarcode is furnished to form the 



Fig. 12. 



Actinosphcerium Eichhornii (Pseudopodia 

 withdrawn). 



pseudopodia. Several contiguous 

 vesicles may contribute to form a 

 single ray, and ordinarily these rays 

 extend outward on all sides. The 

 endosarc consists of many nuclei, 

 and the alveolar structure is not so 

 apparent as in the outer layer of 

 the body. At various parts of the 

 surface of the body-substance, one 

 or more of these vacuoles may en- 

 large, and swell out beyond the 



