No. f)29] 



ORGANIC RESPONSE 



17 



In the experiments of Sumner mice reared in a warm 

 room were found to differ considerably from those reared 

 in a cold room in the mean length of the tail, foot, and 

 ear, and the differences were transmitted to the next 

 generation. The differences may be reasonably desig- 

 nated as being directly individual and somatic, and as 

 having been transmitted by the germ-plasm, which was 

 not subject to the action of various temperatures in the 

 lirst instance. The reaction forms have an additional 

 claim upon our attention, since they are the ones which 

 distinguish northern and southern races of many animals. 

 The crucial test of the value of the alterations induced in 

 the mice is the one applicable to all of the experimenta- 

 tion on this subject, a test in which two parallel series of 

 cultures, one under the altered environment and the 

 other under usual conditions, should be kept going con- 

 tinuously for a long number of years, lots being with- 

 drawn from both, from time to time, for long-continued 

 comparative culture in normal habitat and under other 

 conditions. Effects due solely to fluctuating variability 

 may be expected to reach a maximum and minimum 

 within two or three years, leaving the enduring effects 

 standing alone, or in such relief as to be capable of ready 

 calibration. 11 



Kammerer carried out some tests with salamanders 

 three years ago which have the interest attached to any 

 attempt to interpret geographic or habitat relations. Sola- 

 mandra maculosa is viviparous when it lives high in the 

 mountains and ovo-viparous at lower levels. S. atra 

 is an alpine form and the larvae are large with very long 

 gills. When the latter form was kept at unusually high 

 temperatures the larvae produced resembled those of S. 

 maculosa in its lower warmer habitats. S. maculosa 

 kept in low temperatures and without water showed a 

 cumulation of effects by which the characters of the 



d. Organismen, Vol. 30, pt. 2, p. 317, 1910. 



