E. R. Saunders 167 



3. Between these two extremes there occurs a series of forms 

 conveniently divided into two groups, the partially hoary and the sub- 

 glabrous. 



4. The grades in these two groups, whether homozygotes or hetero- 

 zygotes, differ from the extreme forms (type and var. glabra) in that 

 they exhibit a progressive assumption of the characteristic appearance 

 in regard to hairiness. 



5. The successive stages overlap to a greater or lesser extent in the 

 several grades ; hence periodic observation of the individual as develop- 

 ment proceeds may be necessary in order to determine the grade by 

 inspection. 



6. In the partially hoary grades the diminished degree of hairiness 

 is due to the presence, in place of the factor H found in the fully hoary 

 type, of an allelomorphic and less potent factor H^ (= J of the earlier 

 account). 



7. The rare and hitherto unnamed variety here designated semi- 

 incana is, as its name implies, a partially hoary form, and stands next in 

 the series to the type. 



8. The other partially hoary forms, the mid- and quarter-hoary 

 grades, are both heterozygotes, the former as regards one (Hi) of the 

 two contained factors causing hoariness, the latter in regard to the other 

 factor (K). 



9. The colour couple CR acts as a limiting factor to the H^K couple 

 as well as to the HK couple. That is to say the partially hoary con- 

 dition is only manifested when the whole CRH^K group is present. 

 (In white-flowered varieties of incana and semi-incana the colour couple, 

 though ineffective, is nevertheless present, but for some reason not yet 

 clear the production of anthocyanin in the petals is wholly or almost 

 wholly inhibited.) 



10. The sub-glabrous grades, though giving the general impression 

 of glabrousness, are not completely destitute of hairs. 



11. These grades fall into two groups, showing a different regional 

 distribution of such hairs as occur. Both groups include two grades, 

 the higher showing a slight but still definite degree of hairiness in 

 localised regions either at a certain stage or throughout, the lower, an 

 effect much slighter still, only reaching expression point at certain 

 moments even in the regions in question. In the latter case we have 

 the last stages before total disappearance of the hairs, the upper range 

 limit now rising just above, now falling to vanishing point. 



12. Of the 4 sub-glabrous grades one [(a)], like the mid- and 



