STUDIES ON THE STRUCTURE AND DEVELOPMENT OF CERTAIN CYNIPID GALLS

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Abstract
Mycological and histological descriptions are given of the galls Neuroterus batatus form bisexualis, N. minutus form minutus, Andrieus peticola, A. palustris form palustris, A.futilis form futilis, and Amphibolips confluens. Physiological observations indicate the presence of enzymes (diastase, protease, phytoprotease, amidase, hadro-mase, cytase). The larvae, the inner nutritive tissue, and the gall parenchyma were carefully separated and washed and tested for diastase. The nutritive preparation gives starch digestion even greater than saliva. The source of diastase was not determined, but it may be a product of the unicellular organisms always abundantly present. The acidity increased outwardly from the insect. Any foreign material, such as secretions of the egg, or of the unicellular organisms, or wound hormones from tissue injured by the ovipositor, is a sufficient stimulus to incite growth. Such stimuli cause a copious sap flow to the affected area. The first response is cell division below or around the egg. With increasing irritation, the response becomes graduated until decided areas are noted: first of inactivated swollen disintegrating cells nearest the egg or larva; next, of inhibited cells; next, of rapidly dividing cells; and last, of less active cells with sclerenchyma. Excessive chemical stimuli produce inactivation in the 1st zone. The cells enlarge with abundant sap supply, but do not divide. Outside this zone multinucleated cells due to incomplete mitosis occur. Beyond this meristem is a weakly stimulated region with less cell division. Growth of the gall ceases when "antibodies" of the plant neutralize the effect of the stimuli. The neutralizing zone is marked by the presence of sclerenchyma, a reaction product and not a protective layer. Such a view is upheld by cytological observations of hybrid embryos, graft unions, plant tumors, xylem, bark, haustoria of Cuscuta, and normal embryos. The similarity, in histology, of these galls to other plant and animal tumors is noted.

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