BEHAVIOR AND FUNCTIONS OF THE NUCLEUS 



293 



of nodes as mature animals but the nodes are at first small and all 

 presumably increase in size during the interdivisional period. 

 However, I have seen cultures of coeruleus which consistently 

 produced animals with non-uniform macronuclear chains, some 

 nodes being too large and others abnormally small. The lines 

 eventually succumbed. 



There is some evidence that the size and number of the nodes 

 may vary with the conditions under which stentors are grown. At 

 25 °C Prowazek (1904) found that coeruleus had fewer nodes 

 (average of 8) than at i5°C (12). Following the earlier work of 

 Allescher (19 12), Stolte (1922) pursued this matter quite 

 thoroughly, though with what we would now call a primitive 

 control of culture conditions. For instance, to subject stentors to 

 reduced oxygen he simply grew them in tall cylinders. His results 

 indicated that cell size, macronuclear volume, and nodal size are 

 complex variables which probably both interact and are subject 

 to environmental influence. The results were summarized in a 

 table from which Fig. 83 was derived. Rich food, abundant 

 oxygen, and high temperature were correlated with a large number 

 of smaller nodes, and vice versa. 



HIGH TEMPERArUKE 



MUCH 

 FOOV 



tlJTL£ 

 fOOD 



MUCH OXYGEN 



large cell 

 many nodes 

 Small nodes 

 large arri't 



ol macro n 

 rapid growih 

 & division 



LIT TLB OXraEN 



small cell 

 many nodes 

 large nodes 

 rehiivltj Ig 



cutii. macron, 

 reduced fission 



VOm T£MP. 



Small cell 

 lav nodes 

 larye nodes 

 Small art^t. 



o£ macron. 

 vacLLolaie 

 div'n . seldom 



large cell 

 meditun no. 

 0/ nodes 

 large nodes 

 med- Size macron . 

 large vacuoles 

 rapid division 



large cell 

 /eiv nodes 

 large nodes 

 smaE arri't. 



of macron 

 large vacuotes 

 div'n. seldom 



Fig. 83. Effects of environmental conditions on S. coeruleus, 

 according to and adapted from a table of Stolte's, 1922. 



6. Control of nuclear behavior 



Balbiani (1893) first emphasized that the macronucleus of 

 Stentor does not begin its major performance of coalescence until 

 the oral primordium is well developed (stage 5) and capable of 



