42 KRITrSlI I-'RESIIWATER, JMUZOI'OIIA. 



out its (k'stniction tlie protoplasmic Ijodj cannot be 

 cxaniined. It was on tliis species that Verworn (1888) 

 experinjeiited in order to determijie wlietlier a diffiugian 

 rliizopod had the power of reconstructing or repairing 

 its damaged test. He found that regeneration of the 

 injured oi' completely-removed test, by the pjroto- 

 ])lasmic l)ody, does not occur, although the vital func- 

 tions take theii' course in normal fashion.* The same 

 ol>server demonstrated that the structure of the test is 

 completed, "when fission takes place, at the moment of 

 separation of the new individual. Xo subsequent 

 alterations occur and no after-growth takes place. 





j 



Flu. 57. — Dlffuijia umiolata with plain crown. Bownfss, Westiiiore- 

 land. From a drawin;;: by G. S. West, x 310. 



These conclusions cori'oljorate (Iruber's, on the same 

 ])oint, arrived at from indejjendent observations. 



The s])ecies seems rpiite indifferent to climate oi' 

 altitude. in America. .Leidy found it flourishing 

 al)undantly in swampy ])Ools in Xew .lersey and 

 i'(|ually so at an elevation of ](t,(H)(l feet in Wyoming 

 Tei'ritory. Examples vai'ied in the crown being ])lain, 

 ()i- furnisiied Avith spines — conical, acuminate, oi' acute. 

 The spined form — apparently identical with (jur 

 nwn — occurred in sphagnous pools, together with a 

 variety (\'ai'. olln) distinguislied by the peculiarity 

 of having its spines mostly blunt and tip])ed with a 



* ' Zeitschr. fiir wiss. Zool.,' Bd. xlvi, pp. 4.5.5-401. 



