. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 76 S. A. GUTTMAN tion. A frequency increase was noted. After a length of time the entire heart was radiated, and finally segments 3-9 were radiated while 1-2 were shielded—see Fig. 1. Frequency increases were always great- est for total radiation, next for segments 3-9, and smallest for seg- ments 1-2. Another series consisted of 5 experiments, in each of which 2 excised hearts were placed in a linger howl with the usual 200 cc. of sea water. One of the hearts was shielded and 2-3-minute periods 60 r-. 0 10 20 30 40 50 60 70
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 76 S. A. GUTTMAN tion. A frequency increase was noted. After a length of time the entire heart was radiated, and finally segments 3-9 were radiated while 1-2 were shielded—see Fig. 1. Frequency increases were always great- est for total radiation, next for segments 3-9, and smallest for seg- ments 1-2. Another series consisted of 5 experiments, in each of which 2 excised hearts were placed in a linger howl with the usual 200 cc. of sea water. One of the hearts was shielded and 2-3-minute periods 60 r-. 0 10 20 30 40 50 60 70 80 90 100110120130140150160170 TIME IN MINUTES Fir;. 1. Curve showing frequency changes of Linuiliis heart after radiation of various regions. • frequency; • period of radiation; 1-2 radiation of seg- ments 1-2; 3-9 radiation of segments 3-9; 1-9 radiation of segments 1-9 (entire heart). • if radiation were givrn In the unshielded heart. The usual frequency changes (primary acceleration) were observed for the irradiated heart. The shielded heart also markedly increased its frequency. The in- crease in frequency (expressed in per cent) was usually greater in the unirradiated heart than in tin- radiated preparation—see Fig. 2. An explanation is suggested below. XYhen hearts which did not heat because of injury to the ganglion during dissection were irradiated for 2-3 minutes, the rhythmically heating hearts (shielded) always exhibited a marked frequency Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983. Woods Hole, Mass. : Marine Biological Laboratory
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