1. Yellow seedling, a lethal gene in Asiatic cotton, is a simple Mendelian recessive to normal. It has been discovered three times in three unrelated varieties.

2. Yellow seedling and anthocyanin pigmentation are linked. The cross-over value is about 9 %.

3. Yellow seedling is inherited independently of curly leaf and corolla colour.

1. Curly leaf, cu, and virescent bud, v₁, are two newly discovered genes affecting seedlings. Both of them are completely recessive, and form single-factor pairs with the normal.

2. It is shown that curly leaf and leaf shape are linked, with a crossover value not far from 16·6%.

3. Curly leaf and the following characters are independently inherited: anthocyanin pigmentation, corolla colour, lint colour and seed fuzz.

4. Virescent bud and the following characters are independently inherited: curly leaf, anthocyanin pigmentation, corolla colour, seed fuzz, leaf shape and yellow seedling.

5. From the linkage studies of Hutchinson and the writer, it is concluded that the lint colour genes which they investigated are distinct.

Seven additional types of anthocyanin in cotton are described and shown to be controlled by members of an extensive allelomorph system of which fourteen members are now known in the cultivated diploid Asiatic species,Gossypium arboreum andherbaceum. All seven of the new types were found in China, six in field material, and the seventh as an anomaly in experimental cultures. The information relating to the genetical behaviour of this and similar series, whose manifold expressions do not conform to a single simple seriation, is reviewed from the standpoint of deciding between the alternative interpretations of close linkage and multiple allelomorphism with pleiotropy. Although the cotton series, in which a new ‘pattern’ arrangement appeared under controlled conditions, might have been expected to be a particularly suitable subject for this purpose, it was not possible to reach a definite conclusion on the experimental evidence.