Apkil 7, 1911] 



SCIENCE 



537 



proportionate — one the dominant, the other the 

 recessive type. Two such flies have been bred 

 to the recessive form and have given long- or 

 short-winged ofl^spring — no fly with both types 

 of wing. Inbreeding these longs to shorts 

 again has not yet produced a single fly with both 

 types of wings. Evidently the asymmetrical 

 condition is due to a somatic change that takes 

 place in the development of the individual; a 

 change comparable to that that takes place in 

 the germ cells ■ of Mendelian hybrids. The 

 same explanation .applies to the case of the 

 spotted eyes also. The spotted condition ap- 

 pears therefore to be an ontogenetic segrega- 

 tion. T. H. Morgan 

 Columbia University 



heredity in insanity 

 The fact that nervous and mental diseases 

 are often transmitted by heredity was known 

 to Hippocrates and has since his time been 

 amply illustrated by insane-hospital statistics, 

 but the exact conditions under which such 

 transmission occurs have never been fully 

 understood. A recent study has, however, re- 

 vealed some data which seem to indicate that 

 certain forms of insanity are transmitted from 



actual findings recorded in the study here re- 

 ferred to; these findings, it will be observed, 

 are in fairly close correspondence with theo- 

 retical expectation, which is as follows : 



1. Both parents being neuropathic, all chil- 

 dren will be neuropathic. 



2. One parent being normal, but with the 

 neuropathic taint from one grandparent, and 

 the other parent being neuropathic, half the 

 children will be neuropathic and half will be 

 normal but capable of transmitting the neuro- 

 pathic make-up to their progeny. 



3. One parent being normal and of pure 

 normal ancestry and the other parent being 

 neuropathic, all the children will be normal 

 but capable of transmitting the neuropathic 

 make-up to their progeny. 



4. Both parents being normal but each with 

 the neuropathic taint from one grandparent, 

 one fourth of the children will be normal and 

 not capable of transmitting the neuropathic 

 make-up to their progeny, one half will be 

 normal but capable of transmitting the neuro- 

 pathic make-up, and the remaining one fourth 

 will be neuropathic. 



5. Both parents being normal, one of pure 

 normal ancestry and the other with the neuro- 



D = Dominant. E = Recessive. 

 EE = Neuropathic subject (nuUiplex inherit- 

 ance ) . 



DD^ Normal subject of pure normal ancestry 

 ( duplex inheritance ) . 



DE = Normal subject with neuropathic taint 

 from one parent ( simplex inheritance ) . 



parent to offspring in the manner of a trait 

 which is, in the Mendelian sense, recessive to 

 normal.' The accompanying table shows the 



^"Preliminary Eeport of a Study of Heredity 

 in Insanity in the Light of the Mendelian Laws," 

 by G. L. Gannon and A. J. EosanofE. Eead before 

 the New York Neurological Society, October 4, 

 1910. 



pathic taint from one grandparent, all the 

 children will be normal, haK of them will be 

 capable and half not capable of transmitting 

 the neuropathic make-up to their progeny. 



6. Both parents being normal and of pure 

 normal ancestry, all the children will be nor- 

 mal and not capable of transmitting the neuro- 

 pathic make-up to their progeny. 



