584 Varietäten, Descendenz, Hybriden. 



dividual which develops from it, one can only suggest that nothing 

 whatever is explained by giving another name to a well-known 

 fact. Ever since the time of Darwin, and before, we have known 

 that there was „something" in the germ cells which determined 

 the character of the offspring. We have had a dozen different names 

 for this something and by adding a thirteenth, „Gene", Johannsen 

 has merely burdened us with another cloak for our ignorance. 



Finally, the author makes hisown position clear. With Professor 

 Jennings' contention that pure line cultures are of fundamental 

 importance in many fields of physiology and genetics, the author is 

 in hearty agreement, Like other breeds of facts, „pure line facts" 

 can not become too abundant. Indeed, a priori, he is not opposed 

 to the genotype theory. As a theory it is most attractive, but one 

 can not accept it without proof on that account. Personally, the 

 present writer is one of „that last small remnant" who believe that 

 in a Problem of this kind the proof must be biometric. This means 

 merely three things. In so far as the nature of the material per- 

 mits, all the data considered must be quantitative. The data must 

 be numerous enough that biological relationships will not be ob- 

 scured by the errors of random sampling. The data must be ana- 

 lyzed by logically sound methods. 



Judged by these Standards, the author must express the con- 

 viction that as yet there is no adequate justification for the genotype 

 or pure line theory. Jongmans. 



Harris, J, A., The distribution ofPure Line means. (The 

 American Naturalist. XLV. p. 686—700. 1911.) 



The author publishes following summary and conclusions atthe 

 end of his paper. 



1. The Statement that the means of the pure lines of a popu- 

 lation form a „Quetelet's Curve" is now being made by genotypists. 

 If it is true that an apparently homogeneous population is composed 

 of a large number of slightly differenciated genotypes, it seems a 

 priori not unlikely that their means will be arranged according to 

 „Quetelet's Law". The question which concerns the biologist is 

 whether this is, as a matter of fact, the condition found in nature. 

 The object of the present rather laborious study has been to test 

 the validity of this assertion on the basis of available facts. Roe- 

 mer's data for pure lines in peas are the only passabl}^ satisfactory 

 published series available. 



2. Such a Problem has two phases. It is first necessary to de- 

 termine by adequate Statistical tests that the lines in question may 

 be reasonably regarded as differentiated biologically — i. e., that 

 the differences between them cannot be explained as the errors of 

 random sampling, such as give one a low or a high band at cards. 

 It is then allowable to consider the biological interpretation of the 

 differences. 



3. Two tests for differentiation were applied: a) the mean intra- 

 line variability was compared with the population variability, and 

 b) the signiticance of the deviation of individual line means from 

 the population line mean was tested by a coefficient of individual 

 prepotency recently suggested. Both of these tests indicate sensible 

 and statistically significant differences between the lines. These 

 differences may be said to be distributed according to „Quetelet's 

 law" as the term is loosely used by biologists. 



