1892.] NEW-YORK MICROSCOPICAL SOCIETY. 105 



dashes out of the parent sheath with great rapidity. It leaps out 

 with indescribable activity and is gone like a flash. In appear- 

 ance it is a simple Monad, having an ovate body and a long, 

 anterior flagellum, the flagellum always being at the front. To 

 all appearance it is a Monad, and, if its origin were not known, 

 the observer would be excusable for so classifying it. The mon- 

 adiform germ of the fresh-water Salpi?igceca gracilis is exceed- 

 ingly active for a short time, when it settles down in some pleasant 

 spot and develops a foot-stalk and' a lorica like its parent's. 

 But this brackish-water variety has here made a change. It re- 

 produces itself by transverse fission, it is true, but its flagellum, 

 instead of being at the frontal extremity, is at the opposite pole; 

 and instead of being several times longer than the body bearing 

 it, is shorter than half that body width. This is shown in Fig. 

 3, where the parent is retracted into the back part of the lorica,. 

 and the young, monadiform germ is in the front and apparently 

 upside down. It remains in this position for a few moments, and 

 then, with great deliberateness and slowness, glides up the inner 

 wall of the lorica and gently over the edge (as shown in Figs. 4 

 and 5), when its stiff, motionless little flagellum gets in the proper 

 position, because its owner then places itself right side up. 

 Clinging closely to the parent's lorica, it slowly glides along the 

 outer surface, as in Fig. 6, until it reaches an acceptable resting 

 point, when it proceeds to secrete its lorica, as shown on the left- 

 hand side of Fig. 2. Here, instead of the wild if uncertain and 

 wavering dash for liberty as performed by the embryos of the 

 ordinary forms of the fresh-water members of the group, the 

 movements are exceedingly deliberate and slow, the change being 

 a surprising one to the microscopist that has become familiar 

 with the hurrying and skurrying of the ordinary embryo. 



How these movements are effected I have not been able to 

 learn. They are slow and continuous, but there is no apparent 

 movement of the protoplasm, and no visible amoeboid projections 

 of the endoplasm. The movement also takes place as well when 

 the animals are upside down as when they are in the right 

 position, performed as well against gravity as in its direction. 

 It is probable that the wave-like movements of the lower surface 

 of the embryo needed to produce the onward progression are so 



