■i40 LOCK : STUDIES IN PLANT BREEDING 
male parent much intensified. The pods showed spots and 
flecks of pnrple on a green basis. 
Now a tall form of Phaseolus vulgaris grown by natives in 
Ceylon shows just these same characters of flowers, seed, and 
pod-colour, and this variety has a distinctly primitive and 
relatively unimproved appearance. It therefore seems likely 
that this was a true case of atavism on crossing in the strict¬ 
est sense. Unfortunately all the offspring of the cross-bred 
plants were killed by drought before the flowers appeared, 
and I have not yet been able to repeat the experiment. 
In one of the crosses described by Tschermak a race of 
Pisum arvense with “ rose-coloured ” flowers crossed by cer¬ 
tain white-flowered races of Pisum sativum yielded in 
p ants with exclusively “ red ” flowers, like those of the 
ordinary Pisum arvense. 
In F 2 . Tschermak found the proportion red : rose : white 
to be 239.75 . 83: and in several other cases of similar crosses 
the ratio 9 : 3 : 4 was approached ; i.e., coloured : white - 
6 :1 according to the Mendelian expectation ; and also among 
the coloured forms; reversionary : coloured parental -3:1. 
Tschermak supposed the red colour to have existed as a 
latent rudiment in the rose-flowered parent, and that it was 
rendered evident on crossing ; and he applied to the pheno- 
menon the term Cryptohybridism. The character which 
hns suddenly appears he described as cryptomeric. Simi¬ 
larly Tschermak crossed a race of Pisum arvense having no 
purple spots on the yellowish green testa with a white- 
KS, ”“ fiativum - !a F, purple spots appeared 
, a ° ® Prilag * In appeared : purple spotted seeds, 
less 8 witll0llt P ur ple spots, and white seeds ; doubt- 
Ms m the same proportion. This series is identical with the 
fThVn ‘ he Cr03S PWple -S- by native yellow 
described above (p. 331), and there can be little doubt that a 
similar explanation in terms of gametes can be applied to it.* 
‘»bw’S2rf I £‘ en,, * ll ’ S P,per 1,1 February jest as these pburts (Til w«» 
