92 LIBBIE H. HYMAN 



of substances which induce coagulation; the coagulation is pre- 

 sumably the reverse bringing about the removal or recombina- 

 tion of the liquefying substances or production of coagulating 

 substances. 20 On this point, however, I have no evidence. 

 These changes which are the causes of amoeboid movement 

 and behavior originate within the amoeba, and external stimuli 

 do not act directly to produce those physical alterations which 

 result in movement but they act through the protoplasm of the 

 amoeba. I consider that the reactions of amoeba are similar in 

 kind to the reflexes of higher forms, involving reception of the 

 stimulus, conduction, and the initiation of changes leading to a 

 response, except that here of course, receptor, conductor and 

 effector are not differentiated. I should not at all deny that 

 an external change could bring about directly liquefaction or 

 coagulation and resulting locomotion but I think it highly im- 

 probable that this occurs under the usual conditions of existence 

 of the amoeba. 21 



I am naturally quite unable to explain how the amoeba alters 

 its own metabolic processes, or how it is determined where the 

 local liquefaction in the ectoplasm is to occur. One becomes 

 involved in the old question as to whether living matter is ever 

 able to originate a change or whether everything it does is the. 

 result in the final analysis of changes in the external world. If 

 the first supposition is true that protoplasm is capable of self- 



20 The contraction of the amoeba corresponds to the contraction of muscle, 

 and the putting forth of pseudopodia to the relaxation of muscle. If there is any 

 similarity between the two, contraction in the amoeba may be due to the pro- 

 duction of some substance, since contraction of muscle is accompanied by the 

 appearance of lactic acid. On the other hand, the putting forth of pseudopodia 

 may be the result of the removal of this substance, as in the relaxation of muscle, 

 where the lactic acid disappears, and this disappearance is accompanied by and 

 seems to be dependent on increased oxidation processes. This again is similar 

 to the amoeba, where pseudopodium formation is preceded by increased metab- 

 olism. I am very doubtful, however, that there is any resemblance in detail 

 between amoeboid movement 'and muscle contraction, although there very 

 probably is a resemblance in a large way (infra). 



21 Greeley ('04) found that cations coagulate the protoplasm of Protozoa, and 

 that they cause contraction in the amoeba, while anions liquefy the protoplasm, 

 and similarly anions bring about the extension of pseudopodia in amoeba. 



