all the eyes were removed, only root formation took place. Pieces of 

 potato tubers, from which the eyes had been cut out together with the 

 adjoining tuber parenchyma, formed new eyes on these cut surfaces. In 

 the potato leaves, either a simple formation of roots appears at the under 

 end of the petiole or a tuber swelling, containing starch, or a combination 

 of the two, or a regular small tuber with eyes. 



As a total result of all the experiments for which blossom and fruit 

 stems were also used with success, we may recognize that for regeneration 

 the presence of an abundant reserve material is necessary. Pure white 

 sprouts of different plants formed no roots. Darkening, or removal of the 

 carbon dioxid, prevented regeneration. Since certain parts of the plant are 

 not capable of regenerating one or another organ, even when all conditions 

 are favorable, one is led to the point of view that different substances must 

 be present which determine the formation of any certain organ. Such sub- 

 stances should be thought of in the form of enzymes, which are not present 

 in all cells but are localized in definite parts of the plant body. 



Page 833. In regard to callus formation, which takes place between 

 tlie bark shield and stock, Ohlmann expresses himself in his detailed work 

 (Ueber die Art und das Zustandekommen der Verwachsung zweier 

 Pfropfsymbionten. Centralbl. f. Bakteriol. usw. II, Vol. XXI 1908) as 

 follows : "It seems, therefore, that callus formation may begin only at 

 the bark shield. Sorauer states in regard to this c^uestion that no law for 

 the tearing away of the bark may be determined. According to Schmitt- 

 henner, the trunk splits in the youngest sapwood. I have investigated a 

 great number of plants of widely different species in regard to this ques- 

 tion. It was evident that the cambium remained intact on the bark. In 

 more scattered cases, I noticed that a few cambial cells had remained 

 hanging to the youngest wood. Nevertheless, I have noticed this so rarely 

 that I cannot ascribe any significance to it." It should be remarked here 

 that the author did the budding at a time "when the cambial activity was in 

 full progress." In this case, the author was correct. If the budding is 

 done later, however, then the cases observed by Sorauer become more 

 numerous. 



Page 854. Blankinship describes a bleeding disease occurring fre- 

 quently in Montana (North America) in Populus augustif olia , P. bal- 

 saniifera, P. dcltoides, etc. (Zeitschr. f. Pflanzenkh., Part i, 1908). The 

 trees bled extremely from wounds and this was accompanied by the bleach- 

 ing or yellowing of the foliage. At times the wounds on different axes 

 developed into cavities filled with a gummy, half fluid mass. The exuding 

 sap, laden with bacteria, had a sweetish taste and had often attracted large 

 brown ants. 



A "Jaundice" of the poplar is connected with this bleeding disease, in 

 which bleeding may also appear but more frequently does not. The foliage 

 of the whole tree is bleached and dries up in the intercostal fields. Death 



