THE BEGINNINGS OF LIFE, 465 



obscure evidences of circular striation — whilst at one 

 extremity (posterior) there is a more transparent conical 

 projection. The embryo remains almost motionless, 

 except that about every half-minute a sudden con- 

 traction, with invagination of the posterior part of the 

 body, takes place. In the course of a few minutes an 

 eversion of the anterior portion of the organism occurs, 

 so as to form a sort of collar-like rim, from which a 

 row of about 8-12 stout cilia begin to protrude. These 

 cilia are motionless at first, but they have been seen to 

 begin to play in from fifteen to twenty minutes. 

 Previous to this, however, the sudden telescopic con- 

 tractions had been affecting the anterior part of the 

 body as well as the posterior, so as on each occasion 

 to produce an infolding of the ciliary wreath. By this 

 time also slow movements of the contained granules 

 were seen, whilst two or three vacuoles fi-equently 

 appeared and disappeared. After thirty minutes the 

 organism had often assumed an obovoid form, and 

 become distinctly striated, whilst its ciliary wreath 

 might be seen in full play. It soon anchors itself also 

 by its posterior sucker-like extremity, and continues to 

 exhibit sudden contractions at intervals of a minute or 

 less. The continuance of these sudden contractions 

 whilst the organism is in a fixed position, very soon 

 suffices to produce a pedicle, which pretty rapidly elon- 

 gates. A specimen in which the pedicle was just about 

 to form was kept under observation for thirty minutes, 

 and in this time it was found to have attained a length 



VOL. II. H h 



