LIGHT-INDUCTION OF SHEDDING OF GAMETES IN CIONA INTESTINALIS AND MOLGULA MANHATTENSIS

¹ Johns Hopkins School of Hygiene & Public Health, Baltimore, Maryland

1. The time of shedding of gametes and the effects of the intensity and the wavelength of light upon the process have been investigated in Ciona intestinalis and Molgula manhattensis.

2. The time of shedding was recorded from 24 animals in each species on four consecutive days. It was found that Ciona intestinalis and Molgula manhattensis commenced to shed their gametes 4.07 min. ± 2.60 and 24.16 min. ± 4.46, respectively, after exposure to light. Twelve out of 24 Ciona intestinalis shed on 4 consecutive days and 6 out of 24 Molgula manhattensis shed consecutively over a semilar period.

3. Intensities ranging from 0.21 to 130 foot-candles (f.c.) were used to study light-intensity effects. High intensities did not inhibit shedding but lower intensities —0.67 f.c. and 0.40 f.c.—produced a marked reduction in the shedding response. At 0.21 f.c. shedding was completely inhibited in Ciona intestinalis and reduced to 25% in Molgula manhattensis.

4. In both species, shedding was partially inhibited when light was absorbed up to 600 mµ and totally inhibited when absorbed to 700 mµ. This indicated that the excitatory wave-lengths lie between 500 mµ to 700 mµ.