948 EXPERIMENT STATION RECORD. 



The conditions of success of grafts are divided into two groups, 

 extrinsic conditions, i. e., conditions indepoiidont of the nature of the 

 plant, as soil, temperature, etc., and intrinsic conditions, or condi- 

 tions dependent upon the peculiar nature of the plants grafted, as 

 method of cicatrization, analogy, and l)otanical relations. The extrinsic 

 conditions which it is necessary to observe in grafting by approach 

 are summarized as follows: (1) A temperature sufficient for the pro- 

 duction of the meristem, (2) the prevention of all conditions Avhich 

 cause rotting or drying of the cicatrizing meristem, and (3) mainte- 

 nance of adherence of the wounds b}" the aid of ligatures susceptible 

 of being loosened progressivel}'^ with the growth of the plant. 



Under intrinsic conditions in grafting by approach cicatrization is 

 first considered. Plants cicatrize their wounds either by simple dry- 

 ing of the cut tissues and neighljoring cells or l)y regeneration of tis- 

 sues by the aid of the meristem. The author thinks it may be possible 

 to graft plants by approach which cicatrize the wound by drying up, 

 but this could be accomplished only ])y compression when operating 

 with very young tissue in a way to produce an artificial concrescence. 

 This last method has not l)een tried, but all methods by cutting have 

 failed in the divers monocotyledons and the majorit}^ of the crj^pto- 

 gams. Thus the author has not been al)le to graft Ruscus, ferns, bam- 

 boos, or maize, and hence fornuilates the fourth fundamental condition 

 of success in grafting 1)}^ approach as follows: Grafting ])y approach is 

 impossible with all plants which cicatrize their wounds b}^ desicca- 

 tion of the wounded cells and neighboring tissues — that is to say, are 

 incapable of regenerating their tissue. 



In order to learn whether onl}" plants possessing cani])ium tissue are 

 able to l)e grafted, as generalh" held, the author operated on a num- 

 ber of monocotyledons and cryptogams. A perfect cicatrization of 

 the wound was obtained by the tongue graft with Gladiolus, Funchla 

 cordata^ day lily, PhUodendron^ caladium, white lil}^, Glohh'a coccinea^ 

 etc., but the most interesting result was the success of the cicatriza- 

 tion of Selaginella arhorea. The success of these grafts shows that 

 grafting by approach is possible with certain monocotyledons, and 

 that the presence of the cambium layer is not always necessar}^ to the 

 success of all grafts by approach. 



Under analogy in grafting by approach, plants essentialh' ditl'erent 

 in wood and bark structure are first considered. Borecole and turnip, 

 the structure of which is verj^ difl'erent, were easih' grafted, forming 

 a perfect suture between the ligneous la3"er of the borecole and the 

 medullary parenchyma of the turnip. The difterence in the hardness 

 of woods and their histological nature may not be an obstacle to 

 anatomical union. A natural, distinct cicatrization occurred between 

 the grafted oak and the beech and between the fir and linden; the oak 

 and the ash united by their stems, and the oak and the walnut united 



