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On the Transmission of Environmental Effects. 



animal, influenced by temperature. The length is least when the temperature 

 is highest. 



Experiment 0. — Dealing with the same character as Experiment B, 

 influenced by certain food cultures. 



In the case of A and B it was found that the characters in question were 

 acquired ontogenetically. That is to say, normal specimens were placed in 

 the protophyte culture or high temperature soon after birth, and at maturity 

 showed respectively reflexed valves or smaller size, compared with controls. 



Animals thus rendered abnormal were removed from the stimulating 

 environment into normal control conditions with their eggs ripe for laying. 

 From these eggs, which only underwent their ovarian growth under the 

 abnormal conditions, developed broods (Fi) showing their parent's abnormality 

 very strongly marked. In later broods from the same parents still living in 

 control conditions, the abnormality appeared in rapidly diminishing degree. 

 The next generation (F 2 ) showed a very slight persistence of the abnormality, 

 but F 3 a very pronounced reaction in the opposite direction. In all cases the 

 effects were estimated by comparison with contemporary controls living 

 under similar conditions. 



Over 3000 specimens were measured in Experiments A and B and all were 

 members of the same pure line, all descended by parthenogenesis from the 

 same original female. In C fewer specimens were used, and those were not 

 known to belong to the same pure line. 



From the general results of the experiments it is concluded that in these 

 cases the environment produces its visible effects on the soma by altering the 

 metabolic products included in the protoplasm. These products influence 

 the development of the soma, causing reflexion of the carapace, smallness of 

 size, etc Being also present in the germ plasm, they are passed passively by 

 the gamete into the developing soma of the next generation, and influence it 

 in the same way. Gradually the protoplasm produces antibodies to these 

 toxin-like inclusions, and the reaction seen in F 3 is brought about. 



