MORE COMPLICATED LIFE CYCLES 



117 



formed was named by Hertwig, in 1902, "chromidien," from which 

 the term chromidia is derived, a term now universally employed by 

 protozoologists. According to Hertwig this latter material in actino- 

 spherium cytoplasm is prophetic of the death of the animal, for when 

 it is thus formed the renovation of the cell is impossible (1904). 



Fir.. 44 



P-i\-»^t, 



Arcella vulgaris. 



(After Calkins.) Three individuals in plastogamic union. 

 P, idiochromidia; .V, nuclei. 



Fig. 45 



* .Ik ~ * ^ .A - • • 



■ % ; ftr **•"■ jfc,- / J *. #. ^ 



Chromidia formation in .\ctinospherium eichhornii. (After Hertwig.) A, primary nuclei 

 and chromidia; li, complete transformation into chromidia. 



It thus appears that we have to do with two kinds of chromatin 

 masses in the cell body and no little confusion has arisen in conse- 

 quence of the mixed terminology a])plied to this material, which is alike 

 in origin from the nucleus but very diilVrent in function. Chromidia, 

 in Hertwig's sen.se, is functionlcss extranuclear chromatin, but Schau- 

 dinn and others have u.sed the term to designate the sexual chromatin 

 which is equivalent to the chromidialnetz in Hertwig's terminology. 



