Respiration in Invertebrate Animals. 339 



described by M. Blanchard constitutes not a blood-proper but 

 really a clearly defined chylaqueous system. The presence of 

 this fluid implies the existence of a visceral cavity : it is its nor- 

 mal anatomical locale. 



With reference to the blood-proper of the Cestoid and Trema- 

 toid Entozoa the author will at present only remark^ that if it 

 exists at all, it must be under conditions of rudimentary abey- 

 ance. The following general statements will then serve to 

 convey the corollaries which his recent researches appear to war- 

 rant. In the Cestoid and Trematoid worms the whole substance 

 of the body is pervaded by a highly albuminous but homogeneous 

 non-corpusculated fluid, which is distributed extensively by 

 means of imparietal and irregular conduits under the entire 

 cutaneous surface of the body^ constituting the true apparatus of 

 respiration, and displaying alternate flux and reflux movements 

 under external muscular agency, and embracing in every possible 

 direction the diverticula of the digestive system, and from which 

 it extracts its reinforcements. 



It is adequate in every physiological sense to the ends of 

 a nutritive system. Abounding in albumen it is capable of 

 ministering to the wants of the solids. Though destitute of 

 morphotic elements, it yet conforms to all the essential charac- 

 ters of a chylaqueous system. 



The digestive apparatus (Plate XIII. figs. 3, 6, 7, 8, 9) of the 

 parenchymatous Entozoa is intimately concerned in the process 

 of respiration. In the Cestoid and Trematoid orders it presents 

 but one essential type. It has but one external orifice. A 

 stomach properly so called does not exist. There is this re- 

 markable and apparently anomalous fact to be stated with 

 respect to the fluid with which the digestive cseca are filled: 

 — it is charged with definitely organized floating cells, which 

 exhibit constant dififerences in difi^erent species ! These cor- 

 puscles are not formless molecules. They consist of a cell-wall 

 and granular contents, and frequently a nucleus legible to 

 the eye. They are flat, scaly particles, having a yellowish 

 tinge. They are undoubtedly not fragments from the glan- 

 dular parietes broken ofi" by pressure. They oscillate with great 

 regularity under the rythmic contractions and dilatations of the 

 parietes of the cseca. It is contrary to no analogical argument 

 to suppose that these floating cells are designed to raise the chyme 

 in which they float to an organic standard above that of ordinary 

 chyme. In the parenchymatous Entozoa they execute the re- 

 quired changes in the nutritive fluids, while the latter are yet 

 within the alimentary system. Among the Annelida several ex- 

 ceptions occur in which the same peculiarity is illustrated. The 



