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The Journal of Heredity 



of the plants show the "crazy-top" in- 

 jury, with occasional individuals that 

 remain normal. Thus the mode of 

 occurrence mav indicate an insect-horne 

 disease of the mosaic class, hut with 

 the external symptoms much less strik- 

 ing than in the Chinese and Haitian 

 diseases. 



No Indication of Recovery 



\\'ith this indication that the cause 

 of the injury had disai)i)eared from 

 such areas, greater significance may be 

 ascribed to the fact that the injured 

 individuals continued to grow abnor- 

 mallv instead of recovering as would be 

 expected if the disease were of the 

 temporary nature of plant-louse injury 

 which ceases to afifect the plants as 

 soon as the cause is removed. In India 

 and also in Nyasaland, according to 

 Mr. H. C. Sampson, there is a tem- 

 jiorarv disorder of cotti)n leaves due to 

 attacks of Jassidae. which may serious- 

 ly cripple the plants during the rainv 

 season, Intt after the insects disappear, 

 in the dry season, the plants recover 

 and resume their normal habits of 

 growth. With the Chinese cotton dis- 

 ease all of the plants were afifected, and 

 no indications of recovery were noted. 

 In some cases the later growth ap- 

 peared less distorted, but this was con- 

 sidered as a result of more moderate 

 conditions in the latter part of the 

 season, the amount of distortion being 

 determined to a consideral)le extent 

 U])on the conditions, though the presence 

 of the disease is still apparent in plants 

 that grow with the least distortion. 



In this respect the Haitian and the 

 Chinese diseases may be contrasted. 

 Not only is there a wider range of 

 degrees and forms of distortion in the 

 Haitian disease, but there seems also to 

 be less relation to the external condi- 

 tions. Some of the extreme cases of 

 crippling like that shown in Figure Ki 

 were found in places where the unin- 

 jured plants showed that conditions had 

 been very favorable for normal growth. 



Immunity of the Haitian Cotton 



The so-called native cotton may be 

 of interest in two ways in relation to 

 the disease. The fact that the disease 

 apparently does not injure this type of 

 cotton does not ])rove that the infection 

 might not come from the immune cot- 

 ton. The insects that cause the disease 

 might feed on the native cotton, or 

 even make it their regular home. This 

 would be the more possible because the 

 native cotton is a large perennial bushv 

 plant, often growing to a height of 

 eight or ten feet, with woody stalks 

 often two inches or more in diameter at 

 the base. It is generally distributed 

 about the towns as well as in the rural 

 districts of Haiti, either as a dooryard 

 plant or growing half wild in neglected 

 grounds or waste places. 



Of course, it is possible that a closer 

 study might detect a slight injury of 

 the native cotton, but most of the 

 plants appeared to be quite uninjured. 

 A few cases of plant-louse distortion 

 were observed in the Haitian cotton. 

 Red sj^iders and black-arm were preva- 

 lent and appeared also on the Haitian 

 cotton, with occasional plants showing 

 distinct susceptibility. One plant af- 

 forded a rather striking example of 

 the "rust" caused by red spider, with 

 the leaves discolored and distorted over 

 half the surface while on adjacent 

 plants the red-spider injury was con- 

 fined to small yellowish spots between 

 the bases of the principal veins. 



A notable diversity in form, color 

 and hairiness of the leaves may be 

 ascribed to crossing with Sea Island or 

 Upland types. Several forms of Sea 

 Is'and cotton have been observed in 

 Haiti, and are widely scattered, but in 

 no such abundance as the Bourbon 

 cotton. 



A planting of the Lewis variety of 

 Ci)land cotton from North Carolin-^ 

 was seen on La Gonave Island Septem- 

 ber 17, 1917. and in the same garden 

 a tall, upright, purple "native" cotton. 

 The foliage of the Lewis cotton was 

 very pale green, with the leaves and 

 stems distorted, and the branches very 



