AMCEBA 131 



the food, and is not merely a droplet of water taken in along 

 with it, but a secretum of the protoplasm. There is no 

 special orifice nor even a soft spot in the protoplasm 

 where solid food is taken in. The pseudopodia come into 

 contact with some food -substance; they embrace it, flow 

 round it, meet above and below it, and finally enclose it. 

 Blochmann has described how Amoeba proteus catches the 

 agile infusorian Cydidium glaucoma in this simple manner. 

 The Cyclidium seems to be fatally attracted to the Amoeba, 

 swims towards it, and lies between its pseudopods. In this 

 position it is enclosed above and at the sides by the flowing 

 movement of the protoplasm ; it seeks awhile to escape from 

 the death-chamber, but it is finally enclosed; and, when enclosed, 

 a vacuole is secreted round it. It is evident that the walls of 

 the death -chamber formed of fused pseudopodial processes, 

 were originally part of the exernal layer or ectoplasm, and that 

 in enclosing the Cyclidium or other prey they have become 

 internal, and are eventually merged into the inner substance, or 

 endoplasm, of the Amoeba. .Thus ectoplasm can become 

 endoplasm and vice versa. It would not, however, be correct 

 to say that all Amcebse consist of naked protoplasm without 

 any external limiting coat. Amoeba bi-nucleata, so named 

 because it has two nuclei, is a form with a distinct though very 

 thin pellicle outside the external alveolar layer, and this 

 pellicle may be made evident by certain dyes. Pelomyxa 

 palustris, a very large and rather peculiar Amceba, is described 

 as being covered all over with minute non-vibratile hair-like 

 appendages ; and Amoeba villosa has a tuft of similar append- 

 ages at one end of its body, pseudopodia of simple form being 

 formed only at the opposite end. 



It has recently been demonstrated that the contents of the 

 food-vacuoles, at the time of their formation, are acid, and 

 eventually they exercise a solvent action upon proteid sub- 

 stances, but not, it would seem, upon starches and fats. Thus 

 an Amoeba may be said to be strictly carnivorous. It is most 

 probable that the fluid contents of a food-vacuole are a special 

 secretion of the protoplasm, containing a ferment or enzyme, 

 which has an action analogous to that of the gastric secretion 

 of higher animals. The proteid morsel enclosed in a food- 

 vacuole is gradually dissolved, and disappears, only a small 

 granular residue remaining. This residue is eventually re- 



