METASTASIS. 173 



surrounding tissues in which tlieso bacteria he are not only stained, 

 but other^\'ise disorganized. Nothing of this sort occurs in the 

 crown-gall. The subject is still under consideration. 



The anatomy of one of these metastatic tumors in a very early 

 stage of development is shown on Plate XXX. All the central 

 portion of the section is occupied by the incipient tumor. The 

 wliite lines on the margin mark off the extent of uninfected tissue. 

 The tumor had not yet ruptured to the surface, but would have done 

 so in course of a few days, on the upper part of the section, where 

 the abnormal tissue is nearest to the surface. 



CHEMICAL CHANGES. 



EXCESS OF OXYDlZINd ENZYMES IN THE GALL TISSUE. 



The oxydizing power of extracts from croAvn-gaUs is greater than 

 that of extracts from sound tissues. Tourney showed this for 

 almonds. It was also shown by ]\Iiss Marian L. Shorey in some deter- 

 minations made for the senior writer in 1908, using sugar beets. 

 I'hese beets had been inoculated for some montlis with the daisy 

 organism and bore moderate-sized tumors. The black powder 

 isolated and ]jurified by repeated precipitations with alcohol was intro- 

 duced by knife wounds into the crown of many growing sugar beets, 

 but no tumors resulted. This excessive production of colorless 

 substances oxydizing readily to dark compounds on exposure to the 

 air is to be regarded as a host reaction, and is perhaps due to an 

 increase in the oxidase content. 



In 1909 (Blatter f. Ziickcrrubenbau, XVI Jahrg., Nr. 6) Reinelt 

 mentions that Bartos had observed the gall substance in sugar beet 

 to be somewhat darker than the rest of the beet, and says that he him- 

 self observed that when beets are placed in absolute alcohol or vapor 

 of alcoliol this difference in color becomes more pronounced, the gall 

 becoming very dark, whereas the body of the beet is but little stained. 

 - In some tests made in 1910 the senior writer observed the same 

 difference hut only so far as regards the outer protected surface. When 

 the galled beets were thrown into alcohol the galled parts turned 

 dark almost immediately, while the smooth ])art of the root (pro- 

 tected by a normal bark) remained white. No such contrast was 

 observed, however, when the same beets were sliced so that the 

 alcohol had an equal opportunity to act on all the tissues. These 

 were the beets which served for the illustrations shown on Plate XXII. 



OTHER CHANGES IN THE TISSUES. 



The chemical analyses by Strohmer and Stift (Osterr. Ungar. 

 Zeits. f. Zuckerind. und Landw., II Heft, Wien, 1892) show in the 



213 



