822 
Journal of Agricultural Research 
Vol. XXVIII, No. 8 
varieties. Yet one variety of Asiatic cotton, from India, growing at an experi¬ 
ment station near Wuchang, showed none of the club-leaf distortion, although 
the adjoining rows of native Chinese cotton were badly affected. This indication 
of the existence of an immune variety of Asiatic cotton is confirmed by informa¬ 
tion received recently from China by J. B. Griffmg of Nanking University, with 
the photograph shown in Plate 8. 
In Haiti the Upland cotton was more deformed by the stenosis disorder than 
Sea Island cotton. The so-called “Native Haitian” or Bourbon cotton showed 
no injury from stenosis, while the Upland cotton showed more serious injuries 
than from cyrtosis in China. 
INDIVIDUAL DIVERSITY OF CRAZY-TOP PLANTS 
A general impression of uniformity may be given by the reduced growth of the 
plants in a crazy-top spot, like that shown in Plate 1, but closer inspection shows 
many differences among the adjacent individuals, in the size, shape, and dis¬ 
tortion of the leaves, in the occurrence of tomosis, in the shedding or retention of 
the squares, in the forms and positions of the involucral bracts, in the attainment 
of the flowering stage, and in the development of bolls. (See PI. 2, 10, 11, 12, 
13, 14, and 15.) The diversity may be comparable to that of a hybrid stock, or to 
the wide range of differences that sometimes appears in a stock that is being 
grown under new or unwonted conditions. 
Many stages and degrees of abnormality had been observed in the Chinese 
mosaic disorder, and a still wider range of diversity among the affected plants was 
a feature of the stenosis disorder in Haiti, and a similar diversity appears in 
crazy-top. Though the individual differences are less striking in Arizona than 
in Haiti, they are obvious enough, especially in the Upland varieties, as will be 
seen from the photographs of a few examples, in Plates 10 to 15. 
Such differences might be ascribed to irregularity of cultural conditions, but 
this view is not likely to be held when the differences that appear in adjacent 
plants in a crazy-top area are contrasted with the greater uniformity of the 
normal plants nearby. Little doubt will remain that the diversity of crazy-top 
plants is abnormal, as well as the particular changes of characters. 
RELATION OF GROWTH DISORDERS TO HEREDITY 
The individual diversities of plants affected with growth disorders show that 
many deviations from the normal hereditary course of development are induced. 
The normal characters are no longer brought into expression, but are replaced by 
aberrations or abnormalities of many kinds, differing among the types and varie¬ 
ties of cotton as well as among the individuals of the same stock. Different 
characters are shown, not because the plants have different conditions, but because 
development is disturbed by loss of the normal adjustments or expression rela¬ 
tions that determine the characters or course of development of the individual. 
The changes of expression are somewhat definite, since otherwise the same aberra¬ 
tion would not be repeated so consistently in the structural units of the individual 
plant, while neighboring individuals of the same stock show equally consistent 
expressions of other abnormal features. 
Thus the growth disorders may be of special interest to students and inves¬ 
tigators of heredity, as showing that the expression of the characters of plants 
may be changed by chemical compounds in a manner that may be analogous to 
the recently discovered control of development in animals by secretions of the 
ductless glands. Abnormalities that otherwise would be considered as aberra¬ 
tions of heredity become explainable as effects of poisons or of disturbances of the 
normal sequence in the chemical reactions that attend the process of development * 
