90 LIBBIE H. HYMAN 



that the Brownian movement is greater in the more internal than 

 the superficial granules, and in the tips of the pseudopodia, 

 during or just after the cessation of locomotion, than elsewhere 

 in the ectoplasm. Other evidence is furnished by careful ob- 

 servation of the locomotion under high power. The pseudo- 

 podium advances by little lunges, first to one side, then to the 

 other, just as it should if sudden local liquefaction were occur- 

 ring. 19 This method of advance is more marked, as it should be, 

 in all cases where the ectoplasm is more gelatinized, as when 

 movement starts up in a pseudopodium which has been aban- 

 doned for a little time, or when the amoeba starts to move from 

 the contracted condition, etc. It is also far more obvious in the 

 hay variety then in the wheat variety, and the former, as I have 

 given reason for thinking, has the more rigid ectoplasm. The 

 'eruptive' pseudopodia of Rhumbler and others are the same 

 lunges of the ectoplasm on a larger scale, and appear to be char- 

 acteristic of amoebae with highly gelatinized ectoplasms since 

 the ectoplasm which had previously formed the surface remains 

 visible for some time within the erupted pseudopodium, and 

 forms a barrier to the advance of the endoplasm. These ecto- 

 plasmic barriers are always observable in the amoebae I have 

 examined, particularly in the hay variety. 



I have stated that the withdrawal and contraction of pseudo- 

 podia are processes of gelation. This, I think, follows inevitably 

 if the opposite process is one of solation. The chief other 

 ground for it is that contraction is always accompanied by the 

 appearance of folds and corrugations in the ectoplasm, which are 

 the more marked the more sudden and powerful the contraction. 



19 It would seem to be a simple matter to determine in what part of the pseudo- 

 podium movement is initiated, but as a matter of fact it is very difficult. Har- 

 rington and Learning ('00) state that movement begins in a mass of granules in 

 the middle of the pseudopodium but I am unable to agree with this. I find the 

 movement starting in the clear non-granular ectoplasm, which frequently lunges 

 forward without any corresponding movement in the endoplasmic granules. I 

 am not prepared to explain the forward movement of the surface of amoeba, 

 which has been described by several investigators, most recently Schaeffer ('16), 

 since the various accounts do not agree. I am inclined to agree with Schaeffer 

 that it indicates that the ectoplasm at the tip of the pseudopodium increases at 

 the expense of the surface ectoplasm and not at the expense of the endoplasm. 



