THE COMMON HYDRA OF BENGAL. 345 



sometimes produced, first becoming visible as a minute projection between two of the 

 others and growing out as rapidly as the original five have done. In April, however, 

 and later in the year, only four tentacles (in a few cases only three) are generally 

 produced by a bud. At least three weeks may elapse between the first visible existence 

 of a bud and its separation from the mother polyp ; but I have not seen an attached 

 bud budding or producing gonads. The final division is affected by the young 

 individual bending down and fastening itself to some fixed object by means of its 

 tentacles, which it uses to pull itself free. 



I am doubtful whether more than four buds are produced by an individual in the 

 course of its life. When sexual maturity approaches, budding does not altogether 

 cease ; but it becomes less frequent and is less common in females than in males ; I 

 have not observed an instance in which a bud actually commenced to develop after the 

 appearance of the gonads. In budding males the bud occupies a position at or im- 

 mediately below a vertical line of spermaries. I have noticed on several occasions that 

 the bud of an adult male reaches a greater length before the production of tentacles than 

 it does in a vigorous individual which is not sexually mature. The decrease in vigour of 

 budding does not appear, however, to be directly brought about by the assumption of 

 sexual maturity, but rather to be dependent on a general decrease of vigour due to 

 unfavourable conditions, which also influence the production of the gonads. The same 

 phenomena which I have observed as regards the buds in breeding individuals, I have 

 also observed, after a rise in temperature, in the case of individuals which subsequently 

 died without the appearance of the sexual organs. Towards the beginning of the hot 

 weather, budding always becomes less active and, in some individuals, ceases altogether ; 

 while the same thing happens during periods of temporary warmth in winter. At such 

 times the buds also grow relatively longer before tentacles are produced than they do at 

 the time of active budding during the fall of temperature at the beginning of winter. 

 In December almost every individual taken from the tanks bears a pair of buds, which 

 produce tentacles while still but little longer than broad ; whereas in March it is not 

 very common to find an individual with more than one bud, which may be at least three 

 times as long as broad before the tentacles commence to develop. In the latter month 

 it is as common to find budding parents with only five tentacles, as it is to find buds 

 with only four tentacles in April. In April, it is not uncommon for two or even three 

 buds to be produced ; but between June and October few if any polyps bear buds. 



I have not been able to cause the disappearance or retrogression of buds by 

 starvation. 



In Calcutta specimens (and also, so far as I could see, in those from Pusa) budding 

 is confined to a distinct zone nearer to the aboral end than to the mouth when the 

 animal is not contracted. Given a uniform degree of contraction for the whole body, 

 this zone has a definite and constant position, which, however, cannot always be re- 

 cognized, as the part of the body below it would appear to be more contractile, both 

 in a horizontal and a vertical plane, than that above it. The more solid and indigestible 

 parts of the food are, as a rule, retained in the upper part of the body, apparently because 

 the part below the budding zone is contracted horizontally. Yet the latter region is 



