MISCELLANEA. 



I. Inheritance in l'ltiisedlas vii/(/(iris. 



Professor F. Jüluinusen lias just pulilislieil a summary of liis rcreiit cxiiuriuients uii iuherit^nicc. 

 His work Ueber Erblichkiiit in Populationen und in reinen Linien (Fisclicr, Jena, 1903) is 

 dwlicated to Francis Galtoii, as tlie "Scliiipfcr der exakten Erbliclikeitslehrc" ; it shows tliat the 

 author has rcalised the inipiirtanee of adeciuate Statistical metliods in any attempt to dcal with 

 tlie prol)leui of inheritance, and wo wish to express our gratitnde to liini for the courteous tone 

 adopted in speaking of " Biometriker," and for the patient eftbrt he has made to understand tiieir 

 work. 



Professor Johannsen's niaterial is collected frora three generations of licans: he has (1) a 

 series of individnal socds, chosen mit of a sample of abo\it l(i,OÜÜ, which had been harvosted and 

 mixed together ; these affbrd his evidence concerning the character of a grandmaternal generation ; 

 (2) each grandmaternal bean, when sown, yielded a crop of materual beans, the mean cliai-acter 

 (weiglit or longth-breadth index) of those borne by one plant being taken as the measiire of the 

 maternal character of the line of ancestry to which the plant belongs; (3) from the series of 

 seeds borne by each mother plant, a certain mimber (from two to seven) wcre sown, the n\eaii 

 characters of the seeds borne by the resulting plants being taken as a nicasnrc of the characters 

 studied in the filial generation of each line. 



From these data three principal sets of taliles are constructed ; on p. liö, ('ehersichtstuhcUc 1. 

 givcs material for measnring the regres.sion of individnal tilial Ijcans on the nieiui weight of the 

 maternal beans; a series of tables on pp. 21 — 24 gives the relation between the weights of the 

 individnal beans of the maternal plants, whicli were sown, and the mean weight of the seed 

 produced by every resultant plant ; tinally on pp. 36— 37 a table is given which Professor 

 Johannsen believes to sliow that the progeny of every seed, within a particnlar line of ancestry, 

 exhibits a complete "Rückschlag" to the type of its line, the coefficients of correlation and 

 regi'ession betweeu parent and oftspring within the line being each-0. 



On the basisof these tables Professor .lohannsen attempts to explain the apparent discropancy 

 betweeu Galton's law of regression and the results obtained by de Vries and others: but his \-iew 

 of the consequences supposed bj' "Biometriker" to foUow from Cialton's results shows that he has 

 not fuUy realised what those consequences are. 



It is fully realised by " Biometriker '' that the general regression observetl when wc compare a 

 filial generation with a parental generation is compounded of a series of suli-rcgressions, the 

 members of each line of ancestry regressing to the "type" of their line; the offcct of selecting 

 defiuite ancestry for a small nnmliei' of generations is also recognised ; these points were fully 

 dealt with in 1898, although few biologists seem to have realised tlic f irt ; it was then said : 



" \Ve now see that with the law of ancestral heredity a race with six generations of 



"selection will brecd witliin 1-2 per cent. of truth e\-er afterwards,"* or in other words the 



• K. rearsuu : " On the Law üf Ancestral HiTidity," liuij. Sw. l'ruc. Vol. «2, l.S"J.S. Cf. pp. 3',)7— 

 402, "On the Variabilitv anil Stiibility i.f Sclcctcil Stock." 



