156 



HARDWICKE'S SCIENCE-GOSSIP. 



middle and lower third of the body. This I take to 

 be traumatic, as it is symmetrical. 



9 p.m. — The microscope having been in darkness 

 since the last observation, the point as to whether 

 any details of interest would occur on exhibition of 

 artificial light was now investigated. The two frag- 

 ments were known to be separated by ij inches. 

 By means of a pin-hole diaphragm a pencil of light 

 was suddenly projected on to the body. It was seen 

 to be in a state of moderate contraction, but absolutely 

 motionless ; and although the light was continued on 

 it for ij minutes, no movements occurred. By 

 gently moving the mechanical stage, I now placed 

 the cephalic fragment in the field. As it approached 

 the centre it was seen t:> be absolutely quiet, but 



less active, and shows no signs of fixation to glass or 

 debris at the bottom of the trough. The body, on 

 the other hand, is firmly fixed, and very active. The 

 tentacles certainly appear longer ; the swelling, too, 

 has disappeared. I think this proves that it was 

 only the effect of injury. 



5 p.m. — Body active : arms certainly longer. A 

 foreign body is to be made out in the alimentary 

 canal, which was not there this morning. As the 

 Hydra is on the distal side of the box I cannot get 

 any power higher than § to bear on it ; but from 

 the outline it looks like a small Cyclops. Anyhow 

 there is something in the alimentary canal, and the 

 probability of its being food I should think was 

 great. As for the cephalic fragment, it is shrunken. 



Fig. 95.— Eody (1.40 p.m.) 



Fig. 97.— (2.30 p.m. J 



Fig. 9 3. 



Fig. 99.— (6 p.m.) 



Fig. roc— (9 p.nO 



Fig. iox.— (March 28th.) 



Fig. 102. 



SP* 



Fig. 103. 



instantly it arrived in the central bright spot active 

 contractions occurred. The body was again brought 

 under the influence of light and left there, and it was 

 not till a Cyclops came hurrying by that any con- 

 tractions took place. As a control experiment, a 

 budding Hydra v. in the same trough was treated in 

 a similar way. Active contractions occurred in the 

 parent at once, but not till some time had elapsed in 

 the budding Hydra. As regards the condition of the 

 two fragments, practically no alteration has taken 

 place ; perhaps the swelling on the body is not 

 quite so large. 



March 2Sth, 10 a.m. — This morning the fragments 

 were found to occupy the same position as on the 

 previous evening. The cephalic fragment is certainly 



up, only extending and contracting at different 

 intervals. It shows no sign of active growth, but 

 the wounded tentacle is longer and straighter. 



10 p.m. — The experiment of stimulation with light 

 was repeated to-night with practically the same 

 result. The body did not respond at all to the 

 stimulus, whilst the head did, certainly not so 

 strongly. I fear it will not live long. 



March 29th, II a.m. — On examining the contents 

 of the live-box this morning no Hydra, or at any rate, 

 no divided Hydra, was to be seen. Nor was the 

 body found, although I made observations for the 

 two succeeding days, and on the third examined 

 every few drops contained in the trough in a "pond " 

 slide. Nor was it to be found adhering to any 



