838 



of the grafting of Aesculus rubicunda on Acsculus Hippocastanum, taken 

 from nature. A few weeks after the grafting the new structures on the 

 inner side of the bark strips («/) of the stock had become so extensive that 

 they stood out Uke wings from the scion and produced adventitious buds (a) 

 on the cut surface. 



Copulation and Grafting. 



In copulation, the lower end of the scion and the upper end of the stock 

 are cut slanting, and, when possible, both are of the same size. The two 

 cut surfaces are so fitted to one another that the respective tissues of both 

 coincide. Thus we have here simply two surface wounds. These form 

 complete overgrowth edges which push in between the scion and stock. 

 When the manipulation is well carried out and the space between the wound 

 surfaces very small, the closing of the wound is so perfect that even the 

 microscope can show no spaces between the old wood of the cut surfaces 

 and the compressed connecting tissue. Goppert finds that, in copulation, this 

 connecting tissue dies in a young condition without disappearing, while in 

 grafting, when the union is complete, it remains for a long time organically 

 active. In my experience, no such difference dependent upon the method 

 used has appeared in the length of life of the connecting tissue. In older 

 cases, holes may indeed be noticed, or brown, decayed masses of dead tissue. 

 It seems to me, however, that this would occur in all grafting without any 

 distinction as to method used, if the wound by very careful adjustment of 

 stock and scion has been closed by the wound callus first produced without 

 any subsequent formation of woody parenchymatous connective tissue in 

 the union. Copulation may, therefore, retain the value and the universal 

 application which it has had up to the present. However, I consider the 

 simplest form to be the best and the so-called English grafting, as well as 

 Thouin's methods (Miller, Kiififner, Ferrari, etc.) disadvantageous or even 

 injurious and trifling. 



Cleft grafting may be considered as the most dangerous operation. The 

 stock is usually cut off square and split once, or several times, deep into the 

 wood. The scion is cut wedge shape and so clamped in the cleft that its 

 cambial zone forms the connection between the two parts of the cambial ring 

 of the stock separated by the cleft. In case the wedge-shaped scion is not 

 herbaceous, it will on both sides produce wound walls from the remaining 

 part of its cambium alone. This occurs also on the split edges of the stock. 

 The united connecting masses will endeavor to fill out the space in the old 

 wood. On an average, this succeeds very rarely; in spite of the grafting 

 wax, moisture penetrates into the split from the square cut surface of the 

 stock and easily causes decay or allows some fungus to enter. 



The process of grafting naturally does not depend upon the existence 

 of a definite cambial zone but will be possible also in monocotyledons. 

 DanieP gives an example of this ; he carried out grafting experiments suc- 

 cessfully with Vanilla and Philodendron. 



1 Daniel, L,., Greffe de quelques Monocotyledones sur elle-s-memes. Conipt. rend. 

 1S99, II, p. 654. 



