A. Porter 
37 
rapidly over the gut wall and also over the surface of the food column, 
never within it. I have not seen them mingled with the semi-digested 
fluid in the centre of the lumen of the gut. 
Morphology. 
Amoeba chironomi is very difficult to measure, since its shape varies, 
while it does not always extend itself exactly in the plane of the field 
of observation, and so at times appears thicker than at others. However, 
the bodies of the Amoebae which I have seen are from lop to 18//. long 
and 10// to 12// wide, exclusive of pseudopodia. A pseudopodium may 
measure up to 15// in length. Other forms may be found by subsequent 
observers with different dimensions from these. I will now deal with 
the morphology of the various parts and organellae of Amoeba chironomi. 
Ectoplasm. This is remarkably well seen in the process of formation 
of pseudopodia, when an outflowing of clear, homogeneous ectoplasm 
takes place. Neither in fresh preparations nor in stained specimens 
can any detailed structure be observed, but the ectoplasm is vex-y 
refringent and shows well in life (Figs. 2, 3, 16, 17, 19). 
Figs. 16, 17. Drawings of two separate Amoeba chironomi, made with the aid of the 
camera lucida, from fixed and stained preparations (corrosive sublimate-alcohol, 
Delafield’s haematoxylin). Nucleus shown with nucleolus to one side. Note con¬ 
centration of endoplasmic granules around nucleus and contractile vacuole. In 
Fig. 16, similar concentration of endoplasm at the end of the pseudopodium, which 
is about to become oval. 
Endoplasm. The endoplasm is richly granular throughout, the 
granules being fairly evenly distributed, though slight concentration 
occurs around the nucleus and the contractile vacuole (Figs. 16, 17). 
In life, the pulsation of the contractile vacuole can be well seen. The 
excretory pi’oducts make this vacuole more noticeable, as these products 
