GENUS DINAMCEBA— DINAMCEBA MIRABILIS. 87 



ing along the left side, the fore end causing a sHght protrusion of ectosarc 

 at the head (1). A little later the animal slightly elongated, remaining of 

 the same breadth (2). Gradually moving with an inclination to the 

 left, the relative position of the alga was changed so that it crossed in a 

 slant, sind the anterior end protruded to the right of the hea^d (3). The 

 relative position of the alga continued to change, so that it became trans- 

 verse (4), then gradually slanted in the opposite direction (5), and at last 

 assumed nearly its original position, as seen in cut 6. It next acquired a 

 median position, extending through the length of the animal, as seen in cut 

 7. The creature now extended in both directions along the alga, as repre- 

 sented in the succeeding woodcut (8), until it became 0.36 mm. long by 

 0.128 broad. The movements up to this moment had been slow and 

 uniform, but now the animal rather suddenly doubled upon itself, bending 

 the alga with it, as seen in cut 9. The two extremities of the alga were 

 bent more closely together iintil they were parallel, and their ends pro- 

 truded together from the same pole of the animal, as represented in cuts 

 1 0, 1 1 . In this condition the animal measured nearly the same as origi- 

 nally, that is, 0.24 mm. long by 0.16 mm. broad. Subsequently the 

 right extremity of the alga was drawn into the animal, leading but one 

 protruded, as seen in cut 12, and after a little while this also disappeared, 

 and the animal moved away, with the lower part, as seen in the woodcut, 

 in advance. As the alga was three times the length of the animal after it 

 was swallowed, it must have formed a coil; but this was entirely obscured 

 from view by the abundance of food and other constituents of the endo- 

 sarc. During the process of swallowing the al^a, as may be noticed in 

 the outline figures, the number and position of the pseudopods incessantly 

 varied, In the beginning they were numerous; at one time none, and 

 later but two or three. From the creature doubling upon itself, in the 

 manner represented, it would seem as if the head and papillary end of 

 Dinamoeba were not permanently differentiated, for both subsequentiy 

 appeared together to become the tail end, while an intermediate portion 

 of the body assumed the relative position of the head. 



Indeed, no portions of the exterior of Dinamoeba are constant, 

 although they usually seem to be so. Head and tail appear to be mutually 

 interchangeable, and such also is the case with the processes I have for 

 convenience distinguished as pseudopods and papilla. 



