Transplantation Experiments with Peas. II

Abstract

1. The anatomy and histology of the graft union of etiolated pea stems have been investigated. Five and nine days after grafting, the graft unions were fixed and sectioned. Separation into four types was made between the grafts which grew rapidly or slowly to begin with and those which ultimately did or did not take. The following correlations were found: 2. In the grafts which grew rapidly in the first days, very good approximation between the original vascular bundles of stock and scion was found. When the approximation was poor, the grafts grew slowly to begin with. In the grafts which ultimately took, good development of new vascular connections between stock and scion was found. Such connections were almost or completely lacking in the unsuccessful grafts. 3. To test how far good or poor initial vascular approximation influenced the growth rate of the grafts, some special experiments were carried out which indicated that only the initial growth rate and the period before the scion reaches its maximal growth rate are affected by it. The ultimate maximal growth rate and the percentage of successful grafts were not significantly different in grafts with good or poor approximation. A result corroborating these conclusions was obtained when two graft unions were made instead of one. This also did not alter the maximal growth rate of the scion. Thus in peas the ultimate growth of the scion is not affected by the type of grafting or the graft union.