16 Supposed New Species of Acinetan. 
The structure of the suctorial tentacles, as described by Kent, is 
that of a hollow tube traversed internally or externally by a spiral 
filament or granular crest, which appears as transverse striz 
when the organ is fully retracted. The writer has in vain 
attempted to assure himself of the correctness of this view as 
regards the species under consideration. It may be that a higher 
magnification would reveal the structure above alluded to, but a 
one-twelfth immersion objective’ used under favorable conditions 
of light, etc., and repeated observations have shown what seems to 
be merely a coiling and uncoiling of the entire tentacle, without any 
indication of the large central core figured in Plate xlviii., fig. 22, 
of Kent’s Manual of the Infusoria. The extension and retracting of 
the tentacle appears to be effected by the uncoiling and recoiling of 
the whole organ. 
In working out the method of reproduction of this species, the 
writer was at first entirely misled by discovering a specimen with 
embryos clustered around its anterior end as represented in fig. 4. 
The resemblance of this to the exogenous gemmation said to be 
common in the genus Hemiophrya, at least, and figured in Plate 
xlvii., fig. 8, Kents Manual of Infusoria, was so striking that 
there seemed hardly a doubt as to the interpretation ; and had no 
more observations been practicable, the species would have been 
described as reproducing by exogenous gemmation. The question 
naturally arises: May not others have been misled in a similar 
way, and may not exogenous gemmation be much more rare among 
the Suctoria than has been commonly supposed ? 
The life history of this Acinetan discloses the following stages, 
several of which merge almost insensibly into each other : 
lst. The parent form suffers the loss of its suctorial tentacles, 
which seem to shrivel up and gradually disappear. Fig. 3. 
2d. Internal embryos of a round or oval shape make their 
appearance in considerable numbers in the endosare of the animal. 
Fig. 3. This process is accompanied and preceded by an 
unwonted activity in the granular protoplasm of the parent. 
3d. These embryos escape through the anterior portion of the 
1 Since writing the above, satisfactory observations have been made 
with a magnifying power of 1600 diameters, which have confirmed the 
view here advanced. Indeed there seems no room for doubt so far as 
the present species is concerned, whatever may be the facts in regard 
to others. 
