1918] CURRENT LITERATURE 541 
characters as the size of flowers should be prefaced by an accurate knowledge 
of how such characters vary with relative place position on the plant or relative 
time position in the total period of bloom. 
he authors have been able to isolate and maintain a number of races, 
but further state that “within each race there are further variations, continuous 
in gradation and of the same nature as those appearing in a more mixed popu- 
lation, which are unmistakable evidences of the instability of characters and 
hereditary units.”—MERLE C. CouLTER 
New-place effect.—CoLiins” has performed a rather unusual experiment 
with maize, testing the immediate effect of transferring various races to new 
habitats. We have abundant testimony that it is unwise to go very far from 
home for seed corn, and have generally concluded that local corn has become 
the best adapted to local conditions as the result mainly of artificial selection, 
whether conscious or unconscious. In accordance with this we should naturally 
suppose that to transfer seed would depress its yield (for a few generations 
at least). Coxtins, however, shows that while Texas seed of a given strain, 
planted side by side in Maryland with Maryland seed of the same strain, 
exceeds the latter in yield by 8 per cent; when the two are grown in Texas 
the Texas seed exceeds in yield the Maryland seed by only 2 per cent. It 
seems that the transfer of Maryland seed has acted as a stimulus to relatively 
greater yield. This phenomenon is termed “new-place” effect. It adds a 
further complication to the already perplexing problem of vigor in maize.— 
MERLE C. CouLter. 
Dominance and parasitism.—JoNEs"™ finds support of his theory” that 
dominance accounts for hybrid vigor, from observations on susceptibility to 
parasitism in maize. It has hitherto been demonstrated by several investiga- 
tors that resistance to aaa behaves as a definite heritable factor. JONES 
shows that inbreeding corn serves to isolate certain homozygous races which are 
susceptible to smut ai leaf blight while the more heterozygous ancestors are 
resistant.. He concludes that “‘as in so many other cases, those factors which 
enable an organism to attain the best development tend to dominate.” Thus, 
in general, the most heterozygous corn, which therefore shows the greatest 
hybrid vigor, will be the most resistant. A difficulty arises here, since certain 
diseases are known to thrive best in the most vigorous plants. It might be 
possible to account for this difference on the ground that certain diseases are 
immediately destructive to the host while others are not; although if this were 
true, Jones’s leaf blight disease and smut should behave differently —MERLE 
C. COULTER. 
%” Cottins, G. N., New-place effect in maize. Jour. Agric. Research 12:231~243. 
8. 
1 Jones, Donan F., Segregation of susceptibility to parasit Amer. 
Jour. Bot. 5: 295-300. 1918. 
™ Rev. Bot. Gaz. 66:70. 1918. 
Igl 
