OF ARTS AND SCIENCES : FEBRUARY 14, 1865. 397 



At the moment of systole it rather quickly changes from a broad sphe- 

 roidal figure to one which is globular, and then contracts suddenly and 

 rapidly until it is nearly invisible. The diastole then follows slowly, 

 and during this it passes from a jagged, rounded outline (fig. 3, cv) to 

 a lenticular form (fig. 2), then to a hemispherical shape (fig. 4) with 

 the flattened side next to the posterior end of the body, and finally as- 

 suming a spheroidal contour it remains quiet awhile, until the time for 

 the next systole. If the water is not renewed the specimens become 

 unhealthy, which they exhibit by changing their form, and swelling up 

 into an oval, and finally a globular mass. In such a condition the 

 systole of the contractile vesicle oftentimes occurs five or six times in 

 a minute, and will continue at that rate even when the animal is very 

 much flattened out, and until it bursts or falls to pieces. Tincture of 

 opium stops the action of the contractile vesicle almost immediately, 

 even before the rest of the body is sensibly affected by it. The effect 

 is to swell the vesicle to an enormous size, and then, breaking through 

 the postei'ior end of the animal, it expands to a dimension often exceed- 

 ing that of the whole body before it bursts. 



The mouth (m). That this creature has a mouth might be premised 

 from the manner in which particles of indigo or carmine approach and 

 recede from the body. When the animal is mooi'ed by its flagelliform 

 appendage (Jl), and gyrates about it as if on a pivot, these particles of 

 colored food may be seen to pass along the face of the broad longitu- 

 dinal depression (d), and, striking the body just behind its mid-region, 

 glance off in a backward direction. At the point where the indigo 

 strikes may be seen an obliquely longitudinal, ovate opening (m), which 

 leads into an elongated funnel-shaped cavity (ce). The former is the 

 mouth, and the latter is the oesophagus. The mouth lies altogether 

 within the posterior obliquely transverse furrow {pf), and extends 

 from its anterior to its posterior edge, trending diagonally across the 

 axial plane of the body, from right, backwards, toward the left. Its 

 anterior edge (m}) is broad, and from thence it gradually narrows to a 

 sharp angle, which forms tiie posterior edge. It is so inconspicuous 

 that in all probability it is nearly or altogether closed, except when 

 taking in food ; certainly it is not one of the prominent features of the 

 organism, although one of the most important. When the animal is in 

 a sickly condition, and swollen up, the mouth is easily descried, but its 

 relations are not readily made out, because in tliis state the annular 

 furrows are all obliterated ; yet its connection with the oesophagus at 



VOL. VI. 43 



