252 GENETICS IN RELATION TO AGRICULTURE 
This state of affairs was the starting point of further critical study. 
In order to take account of the effect of selection supposedly in the 
opposite direction, he next examined the progeny of the smallest mother 
beans (about 30 cg.) and found that they displayed no such striking 
irregularity as did the progeny of the largest beans. (Possibly this was 
due to the fact that about 20 plants were grown from the smallest beans 
while the progeny of the largest beans came from only 11 plants.) The 
progeny seeds from the smallest mother beans were weighed individually 
and the data put in the form of a frequency table as in the former case. 
COMBI ichra en ess cuceee itd on Ri O idles aauee rte earroee 15 20 25 30 385 40 45 50 55 60 65 
Numbersosseed ssn ccoo se ees ae oe ee 8 18 71 156 172 127 35 15 3 6 
Theoretical numbers....... pete BOTT ee 139 A621 21057 ln oe 
M = 36.68 + 0.30 cg.; « = 7.33 cg. 
This distribution does not indicate a mixture. Instead it suggests that a 
single original “weight type” of bean was set apart by selection in the 
minus direction. The general result of this preliminary study was cer- 
tainly a sort of confirmation of Galtonian regression; but at the same time 
the doubt was aroused whether the original population was not a hetero- 
geneous mixture from which selection simply sorted out already existing 
“types”. Hence came the question: Will selection of plus or minus 
variants within pure lines bring about the isolation of types and cause 
Galtonian regression? 
This question was answered the following year (1902). A series of 
19 pure lines was used for this investigation. Each of these pure lines 
originated from a single bean from the crop of 1900. In the fall of 1901 
each line was represented by the seeds of one plant. In 1902 he planted 
524 seeds. Every seed was given a number and each plant was harvested 
separately. Each pure line, each plant and every single bean was sepa- 
rately numbered. Thus each individual could be compared with every 
other individual. Johannsen first compared his material as a whole with 
the results of his preliminary study. Having recorded the weight of 
each bean, he arranged the data in groups corresponding to the classes 
of mother beans as in the previous year. 
Weight of mother beans...............; 20) 30 | 40 | 50 | 60 | 70 
Mean weight of progeny.............. 44.0 | 44.3 | 46.1 | 49.0 | 51.9 | 56.1 
Number of progeny seeds............. 180 | 835 | 2,238 | 1,138 | 609 | 494 
Again he found about !4 inheritance and 34 regression of progeny on 
mother beans. He next divided each of these six groups of progeny 
beans into classes according to weight as shown in Table XL. 
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