274 Henry Leslie Osborn, 



slight compression with low magnification, it was possible, though 

 the animal is too thick to permit of entirely satisfactory results hy 

 this method, to see much of the internal organization, the course of 

 the uterus could be seen and followed out. 



The four worms found in the urinary bladder were lying free 

 in the cavity of its right horn. They were immediately removed to 

 salt-solution for further examination. Under these conditions they 

 made no movements whatever. A further examination brought out 

 the fact that the body of each worm was encased within a very 

 delicate membraneous film, so transparent as to permit a view of 

 its external organs which had escaped detection at a first glance. As 

 soon as this film had been dissected away, the worms at once began 

 to manifest a certain amount of activity, which however was limited 

 to a single series of movements and was slow and feeble. Fig. 1 

 shows this series of changes passed through in succession from 

 a to d. 



When at rest the animal assumes the form a, in which the 

 outline is cordate with the apex at the anterior end. Being a view 

 of the dorsal surface of the animal it shows the position of the 

 genital pore, on the left side, and the loops of the dark uterus on 

 each side, seen through the skin. The living worms are bilaterally 

 symmetrical, the asymmetry noticeable in the material after fixation 

 and the action of the alcohols, see Figs. 2 and 3, are artifacts 

 produced by unequal contractions on opposite sides of the body, not 

 seen in the living animal. The outline drawings Fig. 1 b, c and d 

 are taken from free hand drawings from the living and changing 

 worm. The outline in Fig. 1 a, may be regarded as the resting form, 

 during the observations it was the form from which the series began. 

 From this the outline changed to b, the anterior end of the body 

 becoming very broad and the body tapering to an obtuse point 

 posteriorly. The body now shortened in its long axis and took the 

 form c. Finally in d the ends are drawn toward each other, the 

 anterior end becomes pointed again and the posterior end cordate. 



The resting stage immediately follow^s as a result of the 

 contractions which reduce the transverse diameter of the body and 

 extend its long dimensions. After a brief interval this series of 

 contractions is repeated as before. 



These movements did not produce changes in the position of 

 the worm in the water in which they were immersed; the worms 

 remained in one place and successive waves of contraction swept 



