THE LOBOSA 



Although the presence of a defined nucleus is regarded as one 

 of the characters of the class, it has been shown that the nuclei 

 sometimes disintegrate and discharge their chromatin into the 

 cytoplasm as scattered granules. This occurs as a result of 

 starvation in Pelomyxa (Bott [2]), and as an antecedent to the 

 formation of sexual or reproductive nuclei in Endamoeba. 



Chromidia. In addition to the chromatin contained within the 

 boundaries of the nuclei, there may be present in the cytoplasm of 

 many Lobosa irregular scattered granules or a fine network of a 

 substance which gives the same reactions and is probably of the 

 same nature as chromatin. 



In some cases, Difflugia (Fig. 6), the network entirely envelops 

 the nucleus or nuclei, but in others it is separated from the nuclei, 

 Arcella, Cochliopodium, etc. (Figs. 19 and 

 21), by a halo of clear protoplasm. 



These granules are called the 

 chromidia, and the network is called the 

 chromidial network (Fig. 6, ch). The 

 chromidia may arise by the migration of 

 particles of chromatin from the nucleus 

 into the cytoplasm or by the disintegra- 

 tion of nuclei, but it seems probable that 

 in some cases they may arise de now 

 in the cytoplasm. 



The fate of the chromidia is varied. 

 They may either give rise to the nuclei 

 of gametes or of swarm-spores (Centro- 



pyxis), or they may accumulate in groups fc^'f^^oJ^iS? (After 

 and give rise to new nuclei of the Hertwig.) 

 ordinary type in the cytoplasm (Arcella, 



Pelomyxa), in which cases they are called Idiochromidia. Or, on 

 the other hand, they may be associated with the assimilating or 

 vegetative functions of the cytoplasm and disappear when their 

 activity is exhausted, in which case they are called Trophochromidia. 



Refringent and Crystalline Bodies. In many Lobosa crystalline 

 bodies and vesicles containing a strongly refracting substance or 

 fluid occur in great numbers in the cytoplasm. Very often they 

 are far more numerous and conspicuous during the stages and 

 conditions of life when active feeding is in progress than in 

 conditions of starvation or reproduction. They are usually 

 regarded as of the nature of reserve food materials. 



In Amoeba dofleini, Neresheimer (18) found that the crystalline 

 body, proteid in composition, is associated with a trophochromidium 

 which is probably the active principal of its formation. Veley (34) 

 has shown that the refracting bodies of Pelomyxa are proteid in nature. 



On the other hand, Zuelzer (35) has described the bodies 



