272 HOW DO STARFISHES OPEN OYSTERS? 



bore in the shell an opening through which the poison could be injected. 

 However, as we have seen above (c/. 4), no such boring of the shell 

 does, in fact, take place. The action of poison was assumed by Eudes- 

 Deslonchamps, Forbes, Eymer Jones, Bronn, Eyton, 0. Schmidt (in 

 Brehm), and Smiley (following Captain Martin). Hamann attempts a 

 detailed description of the process; but, for myself, I fail to see upon 

 what logical grounds, from the presence of a slimy fluid and the 

 opening of the bivalve, a proof for the secretion of poison can be 

 derived. It is not even shown whether the slime comes from the 

 starfish or from the bivalve, and it is a fact, which anybody can easily 

 observe, that bivalves and gasteropods commence a copious secretion of 

 slime if their soft parts are handled. I have, however, made experi- 

 ments which demonstrate quite certainly that Asterias does not secrete 

 a poison, or, rather, that a maiming of its victim by this means does 

 not take place. A Venus verrucosa was offered to an Asterias which 

 had fasted for about a week, and was greedily taken. Whilst the 

 starfish was busy opening, or, rather, eating this Venus, a second one 

 was offered it. This also was immediately taken and, for the time, 

 held fast, its hunger, after the long abstinence, not being satisfied in 

 a moment. When the first mollusc was finished, and its empty shell 

 thrown away, the second was carried by the tube-feet to the mouth, 

 and brought into the usual position. In a short time this one also was 

 opened, and opened extremely wide, but the stomach of the starfish 

 was not thrown out, the animal being satisfied with what he had in 

 hand. The Venus was now taken away from the starfish, whereupon 

 it immediately closed, and was laid in a dish with sand. It was not 

 long before it disappeared in the sand in the usual manner, and it 

 afterwards continued quite normal. Specimens of Venus were, in a 

 similar way, taken from other starfishes at different stages of the 

 process of opening, and before digestion could commence. The result 

 was always similar to that in the first case described, and the animals 

 showed no trace of maiming or other disturbance. Experiments were 

 also undertaken with gasteropods, and these were even more instructive, 

 because the creatures are much livelier, and therefore promised to show 

 more readily any disturbance of their organism. It was, at the same 

 time, possible easily to observe directly all the details of what took 

 place. I chose for these experiments my old friend Natica (sp. mille- 

 punctata or ebrea). Whilst experimenting I made a not uninteresting 

 observation, which completes in a satisfactory way some work which I 

 had formerly published. In a paper on the absorption of water by 

 molluscs,* I had tried to establish the physiological significance of the 



* ScHiEMENZ, P., "Ueber die Wasseraufnahme bei Lamellibranchiaten und Gastro- 

 poden (einschliesslich der Pteropoden)." 2 Theil. Mitth. Zool. Stat. Neapcl. BJ. 7, 

 pp. 423 472. 1887. 



