328 



The Journal of Heredity 



tion had been more numerous or more 

 active in some parts of the fields than 

 in others. 



It seemed very remarkable to see 

 badly crippled and dvi^arfed individuals 

 with plants on either side tv^^o or three 

 times as tall, of normal stature and leaf 

 formation, even to the top growth. It 

 was plain that injury or infection of the 

 crippled indi\'iduals must have occurred 

 at a rather definite- stage of develop- 

 ment, and that the insects or oth;r 

 agents of infection had been few in 

 number and had worked in the fields 

 for only a short time, or some of the 

 plants would show later injury. The 

 injured individuals showed that the dis- 

 ease had been present for many weeks, 

 and the absence of late infestations 

 could only be taken to mean that the 

 agents for communicating the disease 

 could not have continued their work in 

 such fields, unless it be assumed that 

 the plants are susceptible at a certain 

 age or under some special, temporary 

 condition. 



Varied Forms of Distortion 



The Haitian disease, like that of 

 China, is not manifested by a definite 

 form of injury to the plants, but results 

 in various kinds and degrees of mal- 

 formation, showing that the normal 

 heredity or course of development of 

 the plants is profoundly disturbed. 

 Try to imagine a human disease that 

 could turn all the children of a city or 

 a section of country into cripples, with 

 the dififerent i)arts of the body dis- 

 torted in various ways, or sometimes 

 lacking altogether. In such a popula- 

 tion the preservation of normal hered- 

 ity would be an acute problem. Not 

 only are questions of resistance or im- 

 munity involved in the study of such a 

 disease. ])ut the marked deviations from 

 normal heredity are of interest as 

 showing how the "mechanism of hered- 

 ity" may be deranged. 



The nature and extent of the de- 

 formities may be judged from the 

 photographs and explanations that are 

 given in the legends. Figure 14 shows 

 a plant that was only slightly distorted 



and another that represents a rather 

 frequent type of more severe injury, 

 neither of these plants producing floral 

 buds. More severe crippling is shown 

 in the two p'ants of Figure 15, one with 

 the leaves and flower-buds reduced to 

 very small size, and the other an ex- 

 treme case of dwarfing, with the inter- 

 nodes extremely short. This plant had 

 grown only about four inches after it 

 became affected, the leaves and flower- 

 buds being reduced nearly to micro- 

 scopic size. Earlier in the season both 

 of these plants had produced leaves of 

 normal size and shape, showing that 

 they were not natural or congenital 

 dwarfs, but changed suddenly into the 

 crippled state after a period of normal 

 development. 



Perhaps the most characteristic fea- 

 ture of the disease, as showing that it 

 is dififerent from the Chinese disorder, 

 is the development by many of the 

 afifected plants of large numbers of 

 small flower-buds. Some of these may 

 be restricted to very small size as on 

 the plants shown in Figure lo. but not 

 infrequently the development continues 

 to the flowering stage, some of the 

 plants producing large numbers of un- 

 der-sized flowers from the dwarf buds, 

 as in Figure IG. In such cases abor- 

 tion usually takes place soon after flow- 

 ering, but small distorted bolls are re- 

 tained by some plants. 



As in the Chinese disorder, some of 

 the badly crippled plants have the 

 leaves crumpled or buckled and with 

 irregularly torn or eroded margins, and 

 some plants have leaves with irregular 

 perforations or scars of partially united 

 tissue, very similar to the tomosis or 

 leaf-cut disease of young cotton in the 

 United States, but apparently continu- 

 ing for the life of the plant in these 

 abnormal individuals. Such a plant is 

 shown in Figure 16, with several of the 

 leaves taken separately after boiling, 

 to restore the natural turgidity and con- 

 figuration. 



The reason for considering these 

 widely different abnormalities as symp- 

 toms of the same disease is that the 

 diversity is so general and that there 



