Reactions of ALolosoma to Chemical Stimuli 65 



effect of producing precocious excision ot budding zooids. Many 

 of these zooids were so immature that the budding zone was almost 

 imperceptible, yet they were readily snipped off by the energy of 

 the contraction, or through the agency of the accentuated peristal- 

 is. They usually survived the shock, and were able to swim 

 about on the following day. In many cases where a repetition of 

 the stimulus proved fatal to the parent stem, these prematurely 

 excised zooids recovered. 



Reactions Under Changing Conditions 



With head segment removed all of the characteristic reflexes 

 were given. I was able to stimulate the crawling movement by 

 application of the chemicals at the papillae. This was also true 

 after the animal was depressed by tapping over the cerebral ganglia. 



When the temperature of the water was lowered to 10° C. the 

 reactions took more the form of those given under normal stimuli. 

 The animals endured repetition of the stimulus without fatal 

 results. With the temperature raised to 20° C. it was difiicult to 

 apply the stimulus to all without the reaction being so vigorous as 

 to prove fatal. This could only be done when the animal was 

 stimulated at the prostomium. In these cases the negative reac- 

 tion is so vigorous, especially with the acid, the copper and zinc 

 sulphate solutions, that the animal is thrown directly away from 

 the source of stimulation, and far enough so as to be able to escape. 



If the animals were subjected to very bright dayhght before 

 these experiments were made the solutions invariably proved fatal 

 soon after the first application of the chemical. The influence of 

 the light upon the tissues of the body is such that it increases the 

 toxicity of these solutions if they are applied after the animal has 

 been exposed to the light for a few hours. 



SUMMARY OF RESULTS OF THE EXPERIMENTS 



These experiments show that every movement expressed by the 

 action system of iEolosoma in its native environment may he 

 reproduced under conditions of control through the agency of 

 various chemical stimulations. 



