EVOLUTION, HEREDITY, EUGENICS 541 



tirely new mutants. Mutations were produced with x-rays In 

 barley and corn by Stadler, and in tobacco by T. Goodspeed. 



Blakeslee produced mutations in Datura by exposing the parent 

 plants to cold at flowering time. Goldschmidt (1929) by subjecting 

 early larval stages of Drosophila to high temperature (37° C.) 

 secured quite definite mutations. Further important studies have 

 been carried on by I|il\^fyki4^^3^ Jollos (1930), who claims to produce 

 increasingly graded effects by continued exposure to the same high 

 temperature. 



///. Is There Parallel Induction or Independent Simultaneous 

 Modification of Germplasm and Soma? — Stockard and Papanicolau 

 used alcohol fumes on guinea pig parents, producing corneal irritation 

 and opacity in their eyes; their offspring showed a different type of 

 defect. Types of defects appearing in the offspring were abortion 

 and stillborn litters, nervous disorders, eyelessness and mon- 

 opthalmicum asymmetricum, and body deformations. Parents 

 were unaffected. McDowell and F. Hanson have made important 

 studies on alcoholic effects in mammals, and R. Pearl has concluded 

 that in the fowl alcohol kills the unfit germ cells. 



Standfuss, working with butterflies, and Fischer and Schroder, 

 with moths, produced melanism by use of extreme temperature. 

 Some of the offspring showed the character. Harrison and Garrett 

 induced melanism in Lepidoptera by adding manganese sulphate 

 and lead nitrate to their diet, and found melanism appearing in 

 certain of the subsequent broods. Schroder reported success in 

 modifying the pupation instinct in certain caterpillars, and feeding 

 habits in others, with the acquirements transmitted. Tower re- 

 ported modifications in the potato beetle, as a result of temperature 

 and humidity regulation, which were inherited if applied during the 

 germ cell maturation period, but not if treated at other times. 



Brown-Sequard produced nervous disorders apparently heritable 

 by injuring sciatic nerve, spinal cord, or brain of guinea pigs. But 

 an epileptic condition is often found in the species. 



Kammerer extended the area of yellow on the European sala- 

 mander by use of a yellow background. The effect persisted in the 

 offspring, regardless of any kind of background. Castle suggested 

 simple selection as the cause. Kammerer also was able practically 

 to change reciprocally the species Salamandra atra and S. maculosa^ 

 not only in reproductive habits, but in other respects as well. Modi- 

 fications: i. Number of young greatly reduced (2-7); 2. Intrauterine 



