The in vivo emission spectra of sixteen species of Jamaican fireflies and four species of American fireflies have been measured with a photoelectric recording spectrometer. A simple technique of stimulation with ethyl acetate vapor was found to elicit bright continuous emission over a period of several minutes. Although the luciferin-luciferase cross-reactions were positive in all cases tested, peak intensity wavelengths show distinct species differences, ranging from 5520 to 5820 A. Widely separated emission peaks arise from the thoracic and abdominal organs respectively in the same animal, the click-beetle, Pyrophorus.

We have completed a direct-imaging search for faint companions (FCs) to 23 stars within 13 pc of the Sun using the Hubble Space T elescope Planetary Camera. The strategy of this search changed considerably from that reported in 1996. To maximize the image contrast between potential FCs and a target starÏs point-spread function, we adopted the F1042M Ðlter km, *j D 0.04 km) as the primary (j c D 1.02 bandpass of our search. Although our sensitivity to FCs varied with the brightness of and separation from our target stars, an ultimate 10 p detection limit of within 17A of the fainter targets was m 1042 B 18 achieved. As the end of the main sequence occurs at this detection limit makes our search M 1042 B 12, for FCs to nearby stars the most sensitive yet published. Despite this great sensitivity, no previously undetected FCs were found. Our survey would have detected all stellar companions within 17A of our target stars, except for any lowest mass companions lying within of the brightest (V \ 1.5) targets. 0A .5È1A Applying recent models of brown dwarf spectra and evolution, we Ðnd that our search was sensitive to young (0.5 Gyr), low-mass (less than 10 brown dwarf companions to the fainter targets within 5 pc. M J ) A brown dwarf with mass 40 and age 5 Gyr would have been detected at separations greater than 5A M J from Gl 559A (a Centauri A). Our search was not sensitive to 1 GyrÈold brown dwarfs with masses [5 M J , nor was it sensitive to 5 GyrÈold brown dwarfs with massesOn the positive side, we show the [10 M J . Ðrst direct image of the triple system GJ 1245ABC in which all three components are well resolved. Multiband photometry of GJ 1245C suggests for that object a spectral type later than M7. The measured positions of GJ 1245AC are discordant with those expected from published photocentric-orbit elements. The observed positions of four other multiple systems (Gl 65AB, Gl 244AB, Gl 280AB, and Gl 866ABC) also di †er from those expected from published orbital elements. The discrepancies noted for Gl 280AB are sufficient to resolve the long-standing inconsistency between ProcyonÏs observed luminosity and that derived from the theoretical mass-luminosity relation. F1042M images of the astrometric binary Gl 105A do not reveal the presence of a fourth component, as has been proposed to reconcile the di †erences between the observed location of the M7 V companion Gl 105C and the predicted separations of the perturbing body from two independent astrometric studies.

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