PLATE XXI 



The teratoid tumor strand of Plate XX, which gives rise during its course to 

 more than 30 small tumors. 



Top. Cross section of outer part of right side of stem of tobacco plant shown on 

 Plate XX. P, outer edge of the phloem; E, epidermis; T St, tumor strand, which 

 is bedded in the normal cortex of the stem. 



Bottom. Longitudinal section from upper part of the above tumor strand, more 

 highly magnified, showing it to be a true stele. The coarse-celled tissue at top and 

 bottom is the normal cortex of the stem. The pathological tissues are 5 T, sieve 

 tubes; C, cambium; Tr, trachei; Sp, spiral vessels. 



