THE LAW OF JOHANNSEN. 219 



No one, we should think, likes to call "heredity" of charact- 

 ers" the likeness of a tissue-cell and its two halves, daughters, 

 and compares this likeness to the likeness between two hens. 

 But when the separate cells are free-living individuals, they 

 become in our opinion so much more like hens, that we are apt 

 to overlook, that here the likeness between mother and daugh- 

 ter is not of the same order. 



However, we meet in higher animals and plants another 

 sort of likeness, which is directly comparable to the likeness 

 which exists between mother-cell and daughter-cell, rather than 

 between cells which have only the same genotype. 



The experiments of the Viennesse school of Lamarckians 

 have abundantly shown, that the likeness between parent and 

 off-spring, who both grew up changed by the same peculiar 

 influence, can be interpreted as inheritance. We hear that mice, 

 grown up in high temperature have long tails, and that their 

 children, if they grow up in the same environment, also have 

 long tails. We are told, that a certain viviparous lizard changes 

 its belly-colour from white to red in high temperature, and that 

 the young are born with a red belly, even if the mother, just 

 before giving birth to them, is put in a moderately warm place. 

 And we hear such instances, cited as cases of inheritance of 

 acquired characters. We are apt to make light of such an 

 interpretation and to say that it is no more remarkable, that 

 the young are born red in a hot environment, than that they 

 are born hot. But why should we object so much to seeing such 

 instances brought forth as cases of the transmittance of acquir- 

 ed characters) ? Simply because we suspect these Lamarckians 

 more or less injustly, of meaning characters in the sense of the 

 "unit-characters" of the Weismannian Mendelians, and of think- 

 ing, that they have proved an inheritable genotypic differ- 

 ence, induced by the high temperature. Our experience with 

 Lamarckians is, that they as a rule do not want to attribute 

 such a meaning to their experiments at all, even though they 

 are not adverse to seeing other naturalists rashly jump to such 

 a conclusion. 



