Reciprocal Influence of Scion and Stock. 283 



rieties and find that the stocks exert a well marked influence 

 on ceitain functions of the scion as indicated by constant dif- 

 ferences in the sugar and acid content of the juice. 



Influences of a more conspicuous nature and showing a 

 mutual influence of stock and scion is seen in the grafting of 

 many variegated plants. Timpe in an extensive series of ex- 

 periments has obtained some very interesting results with these 

 plants. Ke grafted the vaiiegated on the green form, and vice 

 versa. The gross observations were supplemented by micro- 

 chemical determinations of the sugar, starch, and tannin contents, 

 in addition to anatomical examination. With Ulmus campestris 

 a decided influence was observed not only in the size and coloring 

 of the leaves but abo in the anatomical structure of the leaves. 

 The variegated leaves became reduced in size almost to that of 

 the normal leaf, accompanied at the same time- by the disap- 

 pearance of the variegations. With Acer plantanus scions with 

 green leaves grafted to stocks of the variegated form become 

 yellowish in appearance and show a poorly nourished condition, 

 while with the variegated scion grafted to the normal green forms 

 the variegations are much later in appearing, the leaves retaining 

 for a much longer time their normal appearance. Similai results 

 were obtained with Acer Negundo. With Aesculus when varie- 

 gated and green forms are giafted together, there appears on the 

 leaves of the green form (whether this is either stock or scion) 

 yellowish spots and stripes, and the leaves are much thinner. 

 These peculiarities persist when the green shoot is used as a scion, 

 but when it is used as stock they, after a time, disappear, 

 Weigelia and Cornus graft with difficulty, but when successful, 

 with Weigelia variegated scions on green stocks grow well, but 

 green scions on variegated stocks are scarcely able to live, while 

 the reverse is true of Cornus. A number of herbaceous forms 

 tried by Timpe all showed an inability of the vaiiegated condition 

 to traverse the area of the graft union. 



The most interesting results on variegated plants are those 

 obtained by Baur. In Abutilon Thompsoni, Baur found that not 

 only is the chlorosis transferable from a chlorotic stock to a green 

 scion, but when a chlorotic scion is used it may spread to and 

 render chlorotic the leaves of the green stock. Baur ascer- 

 tained that this chlorosis is due to a virus which inhibited the 



