xiv] Numerical Aberrations 253 



masked ; for though they may be really indicative of 

 physiological disturbance, these disturbances must be rather 

 of the nature of sporadic events than the consequence 

 of predominating large causes affecting long series of 

 records. 



Occasionally however the effects of such definite causes 

 can be traced in our numbers. One excellent example is 

 provided by the work of E. Baur (24), who investigated 

 the inheritance of variegation of the leaves in Antirrhinum. 

 He found that the green type breeds true, but that the 

 variegated, or " aurea" form gives, on self- fertilisation, a 

 mixture of variegateds and greens. The resulting numbers 

 were 573 variegated and 286 green, showing very clearly 

 the proportion 2:1, variegated being a majority. The 

 question why are the variegated not 3 to i of the greens 

 is, as he points out, readily answered. The missing varie- 

 gated plants are those which would have been pure to 

 the yellow character. Such plants would contain no chloro- 

 phyll and consequently would perish. A study of the 

 germinating seeds subsequently proved that this was the 

 true account, for such an examination gave 77 green, 160 

 variegated, 51 almost or quite without green. The last 

 group all died. Such an observation throws a clear light 

 on the meaning of some at least of those " ever-sporting " 

 types to which de Vries drew attention*. He mentioned 

 in particular the fact that so many variegated types had 

 never been bred true in horticulture. This fact, as Baur 

 indicates, has now found an easy explanation on Mendelian 

 principles, for the homozygous form of the variegated is 

 a non-viable type, and the variegated themselves are per- 

 manently heterozygous. 



In the light of this experiment, and indeed from a priori 

 consideration, it is clear that the non-viability of zygotes or 

 even of gametes bearing special combinations of factors 

 may play a large part in genetic phenomena. Nevertheless 

 with the exception of the case of yellow mice (p. 162) and the 

 peculiar phenomenon recorded in regard to maize (p. 161) 

 I know no large series of numbers which show a consistent 

 departure from expectation. There are however suggestions 



* Mutationstheorie, I. p. 597. 



