Zoological Classification. 365 



exactly what it seems. Next to these animals Professor 

 Huxley places the Phizopoda, with a note of interrogation 

 indicating doubt. In former numbers of the Intellectual 

 Observes* many descriptions of animals of this class will be 

 found, and especially of the interesting forms of Amoeba, so well 

 studied by Dr. Wallich, to whose labours Professor Huxley 

 does not allude. The rhizopod, whether naked or inhabiting* 

 a beautifully-constructed shell, is a little mass of jelly-like 

 material. It can put forth processes which answer many of 

 the purposes of organs and limbs. It can flow round and 

 inclose particles of food, and its substance may, as Dr. Wallich 

 has shown, take the form and condition of ectosarc or enclosarc, 

 according to whether the movements of the sarcode bring* 

 particular portions to the surface, or carry them into the 

 interior. A reference to the description of the Amoeba villosa — 

 a term which, although not indicating a species, is applicable 

 to a condition — given in vol. hi. p. 430, will show that some 

 members of the group possess permanent organs ; and 

 Dr. Wallich ascertained that in some cases the nucleus was 

 inclosed in a distinct membrane. He also found reason for 

 supposing that he had detected germ cells and sperm cells in 

 some of his specimens. It is customary to regard the lowest 

 • rhizopods as homogeneous structureless sarcode ; but further 

 investigation may modify this view. 



In sponges, which very much resemble colonies of amoebas, 

 sexual reproduction has been traced. " Individual sponge 

 particles," says Professor Huxley, '"''become quiescent, and 

 take the character of ova; while in other parts, particular 

 sponge particles fill with granules, the latter eventually becom- 

 ing, converted into spermatozoa. - ''' 



Next the sponges Professor Huxley places the unassorted 

 group commonly called Infusoria. Organisms of very different 

 degrees of development are associated under this inappropriate 

 term, and u othing distinctive, of this group only, can be predicated 

 of them all. They will, no doubt, have to be distributed amongst 

 different groups; and when Professor Huxley instances the 

 contractile vesicle and its associated canals as " eminently cha- 

 racteristic of the Infusoria/' we may ask whether the water- 

 vascular system of intestinal worms and rotifers is not of so 

 analogous a nature as to take away the distinctive characters 

 he appears to claim. From the Infusoria we pass to the hydra- 

 like Polyps, from them to the Actinozoa (or anemones, etc.), 

 then to the Polyzoa, of which the Plwmaiella rejip.ns, described 

 in the Intellectual Observer, vol. ii. p. 271, may be taken as 

 a type. 



In the Polyzoa, a distinct nervous system is recognized, 



* Yol. iii. p. 20. lb. 430. 



