NUCLEOPLASMIC RELATIONS IN ARCELLA 35 



3. OBSERVATIONS AND EXPERIMENTS ON ARCELLA POLYPORA 



a. Origin of the specimens studied 



The studies of these multinucleate Arcellas (fig. 30) were 

 carried on at Johns Hopkins University from March 16 to 

 June 16, 1918, and continued at Cold Spring Harbor, Long 

 Island, from June 17th to August 28th. 



The first specimens were found in a flower pot containing 

 floating leaves of AzoUa caroliniana, in the greenhouse on the 

 university campus. Others were later discovered in a pond 



Fig. 30 Arcella polypora. Drawing showing the structure of a typical speci- 

 men. X 310. 



on the campus and in ponds at Cold Spring Harbor. These 

 Arcellas resembled descriptions of A. discoides, but on examina- 

 tion were found to possess more than two nuclei. 



h. Relations between nuclear number ojid diameter in wild specirnens 



Twenty specimens were fixed and stained on April 1st and 

 their diameters and nuclear numbers recorded. Thirty-four 

 more were measured and their nuclei counted in the living 

 state on June 19th. Table 9 shows the distribution of sizes 

 and nuclear numbers in these fifty-four specimens. Other 

 specimens were collected at this time that measure 23, 24, 34, 

 and 35 units in diameter. 



