1. In a total of 303 males of Tristria puluinata, examined from a population in two successive years, three types of cytologically polymorphic individuals were encountered.
2. The meiotic behaviour of the 21-chromosome bearing individual was orthodox type which on comparative metrical study revealed that the ninth (or seventh or eighth?) pair of autosomes, termed as D chromosomes, is absent in individual which represents the nullosomic condition of the D chromosome.
3. The 22-chromosome bearing individuals include one D or the monosomic D and the behaviour of which is regular but peculiar.
4. The meiotic behaviour of the 23-chromosome bearing individual, which includes the two Ds, is regular like that of the normal Cryptosacci grasshoppers.
5. Discussions have been made as to the frequency, nature and the evolutionary significance of the D chromosome.