170 ADA R. HALL 
at the point, the drop remains liquid for a long time. A fiber 
inserted at the point will cause a current in the drop and the 
action of the cells may be studied. There are a large number of 
cells in earthworm blood which seem to have an amoeboid action 
and may be likened to the leucocytes of higher forms. These 
cells, when contracted, are fairly regular, but long delicate arms 
of cytoplasm may be thrown out. ‘These cells tend to aggregate 
in the liquid around any dust particles or fibers which may be on 
the slide. As other corpuscles come along in the stream and 
strike these clumps they also cling fast. Drew (710), in his 
study of the molluse blood (Cardium norvegicum), finds that 
agglutination takes place there also. He has caused these 
amoeboid cells to agglutinate on cotton fibers. As the cells 
strike each other, protoplasmic strands are formed between 
them, and each cell may then attach to a different fiber. Grad- 
ually shrinkage takes place and the fibers are drawn together. 
The cells of the earthworm blood agglutinate around dust par- 
ticles or fibers in a drop or with each other in smears, since 
friction seems to be the causative factor in this process. Fig- 
ure 7D shows such an agglutination taken froma smear. Figure 
7B shows a contracted corpuscle with eosinophile granules; C is 
such a cell in the expanded condition. There are also present 
in the smears, cells whose cytoplasm shows basophile granules 
(fig. 7A). : 
The question then arises as to just what takes place in the 
blood stream and wound area when a cut is made in the body 
wall. Blood may flow on to a glass slide from a clean, smooth 
pipette without forming a compact plug, but if the same blood 
be poured from a blood-vessel into a cut in the body wall, a plug 
is formed which prevents further flow. We know that mam- 
malian blood is caused to clot by the action of the thrombokinase 
in the cut tissues. If clam blood be brought in contact with 
friction surfaces or cut tissues, its corpuscles agglutinate. Drew 
believes that not only does friction of the cut surface cause this, 
but that some substance formed by the injury hastens the proc- 
ess. The earthworm blood seems to be very like the mollusc 
blood in its power of agglutination, so that in all probability plug 
