Mr. H. J. Carter on the Ultimate Structure of Spongilla. 33 



its habitation; not more to particularize these forms than to 

 show how closely they resemble those of the protoplasm of Spi- 

 rogyrtty when under similar circumstances it also leaves its na- 

 tural habitation or cell-wall and seeks for food elsewhere. The 

 smallest is that which resembles Uvella, Ehr. This consists of 

 a number of minute, monociliated, flask-shaped cells, which 

 adhere by their pointed extremities respectively to a common 

 centre point, whence the whole assumes a globular form (PI. I. 

 fig. Wttyb). They are about yyV^^^^ ^^ ^^ ^^^^ i'^ diameter, 

 polymorphic, and present the granule and contracting vesicles 

 like the monociliated sponge-cell of the ampullaceous sac ; they 

 also enclose particles of food, and on separating from each other, 

 attach themselves by a prolongation of the body to the watch- 

 glass {b)j so that they are but a miniature type of the ciliated 

 sponge-cell. The latter, again, which I have already described, 

 loses its cilium a day or two after it has come out into the watch- 

 glass, and assumes an actinophorous form, becoming at last 

 encapsuled ; previous, however, to losing the cilium, it progresses 

 with the latter in front, and not behind, as when it is set free 

 by tearing up a piece of the Spongilla. The ampullaceous sac, 

 whilst remaining entire, also assumes an actinophorous form, 

 loses all appearance of cilia internally, and encloses food after 

 the manner of Amoeba, All these figures are so like those 

 assumed by the protoplasm of Spirogyra^ when it breaks up 

 and undergoes the changes to which I have alluded, that no 

 doubt can be entertained of both organisms being Rhizopoda at 

 this period. 



Of the sense of feeling in Spongilla^ I have had no manifesta- 

 tions beyond the instinctive acts to which I have alluded, and 

 that wonderful power of opening an aperture through itself, 

 which the sponge-cell of the investing membrane apparently 

 possesses; but in Amoeba Princeps, which is a closely allied 

 organism, I once saw the surface contract and become puckered 

 several times successively, on being pinched by a rotatory ani- 

 malcule {Biglena), an experiment which this animalcule performed 

 for me so satisfactorily, that I have no longer any doubt about 

 the matter. 



The " swarm- spore'' described by M. N. Lieberkuhnf, which 

 appears to me to be a ciliated form of the seed-like body, and 

 the same as the "gemmule'' described by Dr. Grant, I have not 

 yet been able to see ; nor have I been able to see his " sperma- 

 tozoa-like bodies,'^ unless the Uvella-iorm just mentioned be 

 them. 



The formation of the seed-like body, however, now that we 



* Annals, vol. xix. p. 259. f Idem, vol. xvii. p. 407, 1856. 



Ann, ^ Mag. N. Hist. Ser. 2. Vol, xx. 3 



