THE TANGANYIKA PROBLEM. 307 



and had no buds. In such forms, however, sexual elements 

 were already being developed in the manubrium walls. 

 Still later in the season the budding process came gradually 

 to an end, the lake swarmed with jelly fishes, and a large 

 proportion of them were still almost destitute of any manu- 

 brium at all ; but at the same time an increasing proportion 

 were becoming completely manubriated and sexual. On 

 my first expedition to Tanganyika this was as far as I 



Fig. 6. — Still older asexual bud, showing 

 succeeding generation of asexual buds upon 

 the manubrium, a portion of which has 

 already been shed, X Si- 



could carry the life cycle, but on the second I picked the 

 story up again, finding that during September and October 

 the manubriated individuals gradually disappeared, the 

 manubriums being gradually re-formed, while sexually 

 mature individuals now swarmed. The ova and spermatozoa 

 were evacuated, and later I found numbers of small planulae 

 and small medusae which were growing rapidly ; but these 

 showed no tendency to form buds during the autumn, and 

 had, without doubt, been formed from the fertilised ova of 

 the sexual forms. There thus appears to be a distinctive 



20* 



