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[Vol. 87 
are known to be, which if true would provide some explanation for 
the presence of the substance in plants. An increasing number of 
compounds known previously only from plants is being isolated 
from the defensive glands of insects. In our judgment the very 
occurrence of such compounds as defensive agents in animals sug- 
gests that they may (sometimes at least) fulfill a similar function in 
plants. 
Carrion insects, often crowded in their food source, undoubtedly 
interact in subtle competitive ways. To what extent Necrodes, or for 
that matter any other chemically protected carrion insect, makes use 
of its defensive glands in such interactions, remains an intriguing 
unknown. 
Summary 
When disturbed, the carrion beetle Necrodes surinamensis (family 
Silphidae) ejects jets of fluid from the anus. The abdominal tip, 
which projects beyond the posterior margins of the elytra, serves as 
the revolvable turret by which the ejections are aimed. Only contact 
stimulation elicits discharges. The fluid is primarily of glandular 
origin but may contain admixed enteric matter. The gland, which 
consists of a tubular portion and a vesicular sac, opens into the 
rectum itself. Chemical work (to be reported elsewhere) has shown 
the secretion to contain two novel cyclopentanoid compounds (a- 
necrodol and /3-necrodol) as well as lavandulol and several fatty 
acids. Two of the fatty acids, n's-3-decenoic acid and m-4-decenoic 
acid, were not previously known from insects. 
Acknowledgements 
Study supported in part by NIH Grants (AI02908 and AI 12020) 
and Hatch Grants (NYC-191406 and NYC-191409). We thank 
Karen Hicks, Maura Malarcher, and Maria Eisner for excellent 
technical help, and the staff of the Archbold Biological Station for 
personal and professional generosity. Vivian Eisner did the drawing. 
Brady Roach, our principal collaborator on the chemistry of 
Necrodes, helped in the unpleasant task of collecting the beetles. 
