282 Infusorial Circuit of Generations. 



conferval spawns, Src), by bodily enveloping them like a ray-fish 

 (Baya), enfolding the nourishment as if fused around it, and the 

 whole surface exhibiting an incredibly rapid cihary commotion 

 during the ichole ])rocess of digestion. This done, the cloak again 

 unfolds, often appearing like two stipules, e. g. of a Liriodendron, 

 and then closes up again. On drying up, or in search for air and 

 moisture, the animals are often seen to mutually enfold each other's 

 flaps. This cannot, however, be interpreted as a sexual copulation, 

 seeing that in the first place they neither develop any eggs, nor 

 in the second place do they even extrude yolks; but their onward 

 development is by eneystrnent. 



Within a few minutes sucb a full-grown " oyster-grub " is seen 

 contracting its big flap, so as to present the shape of a hat with a 

 warped rim and hemispherical crown, the latter formed by the 

 blunter lobe, which contains the "speck" or "eye," and, contracting, 

 gets hemispherically rounded. Yery soon (with a constant ad- 

 justive quivering of the cflia-like bristles) the whole is rounded into 

 a globe, wherein the doubled inside forms a ciliate hiatus. The 

 latter, soon contracting, closes over. Nothing is now seen but a 

 ball with a clear " germinal speck." In a few hours a douhle con- 

 tour (the outer one granular) is exuded. The speck or "eye" 

 itself now becomes dusky and granular. It increases. It bisects 

 " Gregarina"-fashion. Each pear-shaped segment again acqunes 

 a clear speck or " eye." They elongate, being connected by the 

 blunt ends, — each one tapering to a very soft apex ; and these very 

 large germs or pseudo-G-regarinas at last become liberated, probably 

 as " Faramecium Aurelia" which now appears full-grown on the 

 scene.* 



It is about the length of the Oxytricha, about three times the 

 length of the revolving wool-fringed grubs of the Oxytricha, and 

 by all means more complexly organized than either. It has the 

 shape of the (shoemaker's) last for a very elegant lady's shoe. 

 From one side it therefore gives the figure as of a foot-print (with- 

 out the toes) ; but viewed on edge has a pointed rear end, and in 

 this profile it " takes the name " of Paramecium caudatum ! The 

 ankle of that " last," however, is bevelled away, leaving the instep a 

 ridge. Its oral aperture, not clearly distinguishable, is in the 

 middle, slanting almost longitudinally for about one quarter of the 

 length of the body. It seems to work its way, dashing by vacuole- 

 contraction, while at the same time revolving by a roundabout coat 

 or film of short pubescence, almost too delicate to be made distinct. 

 In what appears to be the abdomen it has the well-known circular 

 jpulsatory vesicle, wherewith it propels itself, and around which 

 point it is often seen spinning like a wheel. A system of fusiform 



* The developmental experiments were made in small parcels, forming a drop 

 (between glass slips, somewhat held apart) and preserved from exsiccation. 



