346 



DR. N. ANNANDALE ON 



very nearly as wide as the former when the alimentary canal is empty or the food swal- 

 lowed not of a bulky nature. On the other hand, when the whole animal contracts, the 

 region below the buds becomes relatively less extensive than it was before, and often 

 almost disappears. 



Within the budding zone, which has a small vertical 

 height, the buds appear in a definite order, at any rate during 

 winter. Two are never produced simultaneously, although 

 as many as three may be attached at one time. This order 

 is illustrated in the accompanying diagram, which is based 

 on a large number of observations made on both freshly 

 caught and captive specimens. The circle represents a 

 transverse section of the body through the budding zone, 

 while A, B, C, and D are imaginary quadrants. If the first 

 bud be produced in A, the second will be in C, the third in 

 B or D (I think usually B) 1 and the fourth in the remaining 

 quadrant. As regards vertical position in the zone the arrangement is not quite so 

 regular. The second bud is generally a little higher than the first, the two representing 

 respectively the upper and the lower limits of the zone ; but the third, although it is 

 usually intermediate in vertical position between the first and the second, may be 

 almost in the same horizontal plane as either of them. The fourth is neither higher 

 than the second nor lower than the first. Although this comparatively regular order is 

 a rule to which I have not seen an exception during the winter months, it disappears to 

 some extent at the beginning of the hot weather, when the habits and physiology 

 of the animal become largely disorganized. 



Comment may be made on several points in the above account of the bud- 

 ding of Hydra oriental is. 



In the first place, the small number of buds produced by an individual and their 

 slow development afford evidence of a lack of vigour, which is also illustrated by the 

 small number of tentacles, the lack of adaptability in the adult polyp and the rare 

 production of eggs. 



The fact that the first five (or four) tentacles are, as a rule, produced simulta- 

 neously is interesting as showing a condition of affairs to some extent intermediate 

 between the two extremes which appear to occur in European forms. Haacke (op. 

 cit.) bases his classification of the species which are not green on the order of pro- 

 duction of the tentacles in the bud ; H. tremblyi producing six tentacles simultane- 

 ously, while in H. r ossein these organs appeared in an order related to the orienta- 

 tion of the bud and its parent. 



A third point that may be noted is the position and order in which the buds are 

 developed on the parent. Probably the small number of the buds and their slow de- 

 velopment permit this process to be investigated more easily than would be the case 

 in a more robust form. Evidence, which is to some extent corroborated by the 



I For a general account of the developments of buds in Hydra see Chun in Bronn's Thier-Reichs, Vol. II, part II, 



Coelenterata, p. 243. 



