The Stigmatic Secretion of the Sweetpotato

Abstract

The stigmatic exudate of sweetpotato, when removed with organic solvents, consisted chiefly of lipid and phenolic compounds. Only traces of sugar were obtained. The esterified lipids were similar in chain length to capric and lauric acids. The two prinicpal phenolic compounds have UV absorption peaks, and bathochromic shifts on ionization with NaOH similar to those of esters of caffeic acid. On acid hydrolysis, caffeic acid was obtained from these and from three minor phenolic compounds. From two of the minor phenolic compounds, glucose was released by hydrolysis. The phenolic content of stigmas increased up to 20–24 hr before anthesis, and then gradually decreased. Neither compatible nor incompatible pollination affects the amount or composition of the stigmatic exudate.

Interactions of Electroless Catalysts with Photo‐Oxidized Polymer Surfaces

“…For instance, Martin (1) showed that a chromate paint can prevent electroless deposition by inhibiting the catalyst. Sharp (2) proposed that selective deposition could be accomplished in the "two-step" catalyst system, reactions [1] and [2], by photochemical oxidation of the Sn(II) reducing agent, reaction [3], thereby allowing reduction of catalytic Pd, reaction [2], only in unoxidized (shielded) regions Substrate + Sn(II) (aq) ~ Substrate-Sn(II) [1] Substrate-Sn(II) + Pd(II) (aq) ~ Substrate-Pd(0) + Sn(IV) (aq) [2] hv Substrate-Sn(II) ~-~->Sub strate-Sn(IV) [3] U2 He successfully applied this technique on a variety of substrates, such as polyimides, polyesters, epoxy, phenolics, and ceramics (2). Schlesinger studied the two-step system in detail (3)(4)(5)(6)(7)(8)(9), showing that catalyst activity is dependent on many factors.…”

Nectar and the Nectary of Phaseolus vulgaris L.1

“…The presence of phenols in the nectar may be related to chem ical protection, perhaps against chewing insects. This has been suggested for flowers in which stigmatic exudate phenols have been identified (28,29,30,31,32). Phenolic compounds not only repel some insects but may also impede spore germination (but cf.…”