miscellaneous: stimuli underlying tumor-formation 561 



ably also in some of their neighbors, or, to express it in another 

 way, it is the liberation of an excess of hydrogen-ions in such 

 cells. This leads to a whole train of phenomena whereby a 



Fig. 421.— Section of outer one-half of Fig. 419 at T. Vascular tissue in 

 center. Outer portion of the stimulated (hyperplasia!) layer at bottom. This 

 also contains starch but not as much as the inner portion. 



normal cell (young enough to respond) becomes a tumor-cell, 

 and is consequently more or less emancipated from physiological 



hypertrophied layer directly in contact with the feeding insect; (7) section of the 

 larva. Section cut and stained by Lucia McCuUoch. Photomicrograph by the 

 writer. Medium magnification, 8 mm. apochr. obj., 4 oc, bellows at 40>2- The 

 inner layers have taken most of the acid fuchsin stain. 

 36 



