ANIMAL BEHAVIOR 



of water under the microscope; introduce into their midsl a bit 

 of food substance, and they rapidly collect around it ; this be- 

 havior appears to exhibit marked intelligence until we e 

 ment further and find that we may introduce a non-nutriti 

 body, such as a bit of paper, and they will collect about it in 

 precisely the same way. Note the manner in which many 

 Ciliata sweep the food into their mouths by their rapidly vibrat- 

 ing cilia ; they exercise no choice in the substances swallowed; 

 anything which may be carried along in the current of water 

 passes in, whether nutritive or not, grains of carmine as readily 

 as food. Kxtended experiments on the Protozoa tend to snow- 

 that they do not profit by experience, and lead us to believe that 

 in these simplest animals consciousness is extremely improbable ; 

 although their behavior is often very complex, it is probably in 

 all cases merely a direct response to the stimuli, often them- 

 selves complex, of their environment, and hence may eventually 

 be shown to be explicable by physical and chemical laws. 



Let us look at some of the activities of somewhat more com- 

 plex organisms. The leaf of the Venus' flytrap closes on the 

 insect which alights on its surface, pours out digestive fluids and 

 absorbs the insect. The tentacles of the sea anemone or the 

 coral polyp contract over a bit of food which comes to rest on 

 its oral disc and force it into the mouth. In both these instances 

 we have complex reactions to a certain stimulus, but most 

 scientists would hesitate to attribute consciousness as the term 

 is commonly understood to the plant leaf, and the reaction of 

 the polyp is very similar ; each is a direct response to a given 

 stimulus, which passes directly to the parts which respond ; it is 

 not even as complicated as a reflex action, which can only occur 

 when both afferent and efferent nerves as well as a nerve center 

 have been established. The plant has no nerves and the trans- 

 mission of the stimulus from cell to cell must take place through 

 their protoplasmic continuity ; the polyp has nervous tissue, but 

 of so diffuse a structure that stimuli pass directly from the part 

 affected to the part which reacts. 



Why there are responses to various stimuli is a question we can- 

 not yet answer, any more than we can tell why certain chemical 

 elements will combine with some substances and not with oth> 

 The hen's egg, when laid, consists largely of lifeless substances 



21 



