298 ZOOLOGY: M. BUNTING Proc. N. A. S. 
continued slowly; the cytoplasm became homogeneously refractive and 
the nucleus was obscured probably due to a "gel" state (fig. 1, E). The 
contractile vacuole continued to pulsate slowly ; an involution of the lateral 
margin near this organelle was formed which terminated in the protoplasmic 
body as a cleft. The animal now assumed an elongated somewhat pyri- 
form shape, the margin near the vacuole being flattened. From this area 
flagellar activity began, and thus it became oriented as the anterior end. 
The nucleus, nearer the posterior end of the animal became demarcated 
from the homogeneously refractive cytoplasm (fig. 1, F). The animal 
began to move rapidly, undergoing many contortions, during which the 
cytoplasm became resolved into refractive granules suspended in a clear 
substance, the nucleus moved towards the anterior end and the pellicle 
became more firm so that the flagellate shape was assumed (fig. 1, G). 
The fiagella had reached the average length and the characteristic rota- 
tion around the longitudinal axis began as the animal swam swiftly 
about. 
6. Division of the Flagellate: — In a short time after the above de- 
scribed change the animal suddenly became broadly triangular in form 
(fig. 1, H), flagellar activity being observed at each angle limiting the 
anterior end. The animal then passed into the "gel" state and this was 
followed by longitudinal division (fig. 1, I, I'). The entire transforma- 
tion, followed by fission in the above case, was completed in one hour, but 
these processes are not always so rapid. The flagellate may continue to 
multiply for several hours or even days commonly dividing into two by 
longitudinal fission but occasionally into three or four equal or un- 
equal offspring. 
7. Transformation of Flagellate into an Amoeba: — Eventually the 
Tetramitus transforms into an amoeba unless death prevents. The 
morphological changes which form this sequence are not always the same, 
but one set of observations will be given in detail. A Tetramitus suddenly 
shortened and became broadly triangular, two short processes were pro- 
truded from the angles of the flattened anterior end (fig. 1, J). Soon 
the body became rounded, the processes longer (fig. 1, K),. and the move- 
ments slower resulting in but slight changes of location. Meanwhile 
the protoplasm exhibited external form changes marked by contortions of 
the body. The successive changes were very rapid and suggested that an 
effort was being made by the animal to free itself of fiagella. Finally it 
became quiescent a few moments and then changed into the form of the 
typical amoeba which progressed by a pseudopodium of lobose type in- 
stead of by fiagella (fig. I, L). Another series of changes are indicated 
by fig. 1 , J K' and L'. The transformation process is sometimes prolonged 
through many hours. The amoebae thus derived may multiply by division 
but ultimately they become encysted completing the life cycle. 
