230 Kon-hokiblc Races. 



choice was largely determined by the fact that there 

 were no published records of 4- or 5- foliate leaves of this 

 clover,^ which means that the character, if present in a 

 latent state, is much rarer than in the red clover. 



I take this opportunity of calling attention to the 

 inestimable value of PENZio's^'Teratology." This lies per- 

 haps rather on the negative than on the positive side, 

 for it is of course possible to collect the main literature 

 relating to a given question oneself, although not witli- 

 out the expenditure of a great amount of time; but if 

 one is not a teratologist by profession, it seems hardly 

 possible without some such help, to satisfy oneself that 



^•^ 



Fig. 45. Trifolium incarnatum, 4- foliate leaves, the middle 

 one with incomplete segregation of a lateral leaflet. 



absolutely no records relating to a particular phenomenon 

 exist. 



The first step in a purely scientific breeding experi- 

 ment evidently is to find out whether the deviation in 

 question has occurred before, and if so, whether it is rare 

 or common. My belief is that the commoner anomalies 

 are heritable characters with a high index of inheritance 

 (often about 30-40% or more), but that the rarer ones 

 are the occasional expressions of latent or semi-latent 

 characters. These are also inherited in their latent state, 

 and if they turn u]) here and there this latent condition 

 must ])robably be widely distributed. 



' O. Penzig. Piiansenteratologic , Vol. T, 1890, p. 385, where T. 

 incarnatum is not even mentioned. 



