1. Copulation between individuals of the two species O. moubata, and O. savignyi may occur, and the stimulus of coition may induce oviposition, the eggs being non-fertile.

2. There is no evidence of parthenogenesis in this species, nor do these ticks undergo ecdysis after reaching maturity.

3. An increase in temperature of 8° C. from 22° C. (a) doubles the.rate of oviposition, (b) decreases the fertility of the eggs by 30 per cent., (c) reduces the longevity of the female tick from 715 to 397 days, i.e. by 40 per cent, and (d) approximately halves the period required for metamorphosis, under laboratory conditions. Under these conditions at 37° C., reproduction is inhibited, and the longevity of the female is reduced by 80 per cent.

4. An individual may undergo from four to eight ecdyses before reaching maturity, the great majority of the males appearing after the fifth ecdysis and the females about equally after the fifth and sixth ecdyses.

5. Engorgement can take place one or two days after emergence, at any stage, the average time required being three-quarters of an hour. There is great variation in the extent of engorgement at each stage, but this is not correlated with the ecdysis period. The largest meal may be taken either before or after an individual reaches maturity.

6. Moisture has an adverse influence on the vitality of the individual, excess of moisture inhibiting growth.

7. An approximation to the stage of development attained can be made after the study of the structure of the hypostome, leg and spiracle. The larval and first four nymphal stages are fairly well differentiated, much more so than the later stages, but variation due to nutrition requires further study.