39 ELERY R. BECKER. 



the Euglena. The protoplasm of the amoeba closed over the 

 entrance, the Euglena struggled a bit, then doubled up, and a 

 food vacuole was formed around it (Fig. 22). Such ingested 

 Euglenx are often digested, although sometimes they are egested 

 very soon after entering the amoeba. The process of digestion 

 can be followed. First the Euglena gradually loses its green 

 color, becoming brown in an hour or so; then it is reduced in 

 size, and finally after many hours only some brown undigested 

 remains are left in the food vacuole. The vacuole shows the 

 acid reaction up to the end of the process, as proved by its in- 

 tense redness to a very weak neutral red solution in the water. 



Thus, while normal feeding reactions have never been observed 

 in enucleated amoebae, nevertheless, food may be ingested by an 

 amoeba, the organism ingested entering the amoeba by its own 

 efforts, and not by any positive activity on the part of the amoeba. 

 This method of feeding certainly does not call for concerted 

 streaming. The inability of the amoeba to form a food cup seems 

 to be due to the lack of pressure from within sufficient to sustain 

 the pseudopods engaged in the circumvalation of the food par- 

 ticle. Food once ingested can be digested by the amoeba after 

 the fashion of normal amoebae. 



In five instances not included in the sixty-four experiments, 

 the enucleated fragment of the amoeba had divided spontaneously 

 in from twelve to forty-eight hours after merotomy. The 

 writer chanced to see one such fragment stretched out as in Fig. 

 23. The streaming was essentially like that of two Umax amoebae 

 jointed at their posterior ends. The neck joining the two be- 

 came narrower and narrower, until the edges rounded off (Fig. 

 24), leaving two fragments moving in a Umax fashion (Figs. 25 

 and 26). 



While this is not, of course, normal cell division, it is interest- 

 ing to note that a cell without a nucleus may divide. The divi- 

 sion appeared to be due to the pull exerted in this region by the 

 two halves tending to move in opposite directions, and an ac- 

 companying increase of surface tension at the point of division. 



CONCLUSIONS. 



Enucleated amoebae of the species Amoeba dubia show the 

 following properties: 



