344 DR. N. ANNANDALE ON 



(i) Fission — 



I have only seen three instances of this process, in all of which the split was vertical. 

 In two cases the first indication noted was that the polyp had ten tentacles. A close 

 examination showed that the tentacular area was elongated in a horizontal plane. A 

 minute notch then became apparent at each side, dividing one group of five tentacles 

 from the other. The notches increased slowly in extent, towards one another, and 

 simultaneously two mouths were formed ; until, after two days, the crown had been 

 completely separated into two portions. The split then extended vertically downwards, 

 until a double-headed form had been produced. 



Neither individual lived long enough in captivity to be completely divided ; but 

 there is no reason to doubt that this would have occurred in natural conditions. 



The third case was not observed until the separation was nearly complete, the 

 two individuals merely adhering to one another by means of the ectoderm of the basal 

 disk. Each of them had three fully-developed tentacles, while a fourth appeared in 

 each as a minute outgrowth on the side where the split had taken place. One individual 

 was only about half the size of the other. 



In one of the first two cases I have reason to believe that the polyp had been in- 

 jured by a Chironomid larva, which had attacked it ; in the others I have no evidence 

 of any injury. It seems possible, however, as natural fission is never very common in 

 Hydra, that it may be due, at any rate in many cases, to an accidental injury or to 

 disease in the first instance. 



As regards the Calcutta form, I have not succeeded in producing artificial reproduc- 

 tion by fission experimentally ; but this is what might be expected ; for the form 

 is so delicate in captivity that even under the most favourable conditions it is difficult 

 to keep it alive. There is every reason to suppose that in normal circumstances 

 severed parts of the individual would grow into complete individuals, as is the case 

 with northern forms. 



I have seen one young individual in Calcutta in which one of the tentacles was 

 bifid at the tip. 



(2) Budding — 



Budding takes place more sparingly than it does in some forms. In Calcutta I 

 have never seen an individual with more than three buds attached, and rarely one 

 with more than two. At Pusa, however, as already noted, I saw a polyp, probably 

 belonging to the same form, with four buds attached. Probably buds are seldom 

 borne at all during the hot weather. Especially towards the end of the season of 

 greatest activity (i. e., at the beginning of spring) it is very common for only one 

 bud to be produced at a time. 



The buds first appear as conical projections, at the extremity of which, during 

 winter, five tentacles are produced simultaneously. The development of the tentacles 

 takes place rapidly, and they become elongated in the course of a few hours at most 

 after their first appearance ; but the bud may remain as a simple projection for some 

 days before they appear. Before it separates from its parent a sixth tentacle is 



