Are Genes Linear or Non-Linear in Arrangement?

1 Contributions from the Bermuda Biological Station for Research, No. 113. 2 Crozier, W. J., and Arey, L. B., " Sensory reactions of Chromodoris zebra," J. Exper. Zool., Phila., (in press). 3 Crozier, W. J., 1919, J. Gen. Physiol., Baltimore, 1, No. 6. 4 For more detailed treatment of the complex conditions here entering, consult papers cited in footnotes two and three. 6 cf. Parker, G. H., 1919. The Elementary Nervous System. (Philadelphia.) 6 Frolich (Zs. AUgem. Physiol., Jena, 11, 1910, p. 269) had already demonstrated that in Aplysia the site of action of strychnine is the 'cerebral' ganglion. 7 Cushny (Quart. J. Exp. Physiol., London, 12, 1919, p. 153) points out that the depression of the reflex thresholds, rather than, as often held, the conversion of 'inhibition' to 'activation' (where reciprocal innervation is involved), is the essential feature of the strychnine effect. 8 This conception of the nervous organization of Chromodoris agrees with the opinion held by Bethe respecting Aplysia, but the evidence here relied on is much more complete (cf. Bethe, AUgem. Anat. u. Physiol. d. Nervensystems, Leipzig, 1903).