No. 3-] LOXOSOMA DAVENPORT/. 36 1 



The structure of the muscle cells has been made out only in 

 the case of the longitudinal and oblique muscles of the stalk. 

 It is best shown by preparations stained by methylen-blue. 

 The nucleus is situated at one side of the fiber, and usually at 

 a short distance from it, surrounded by a small amount of cyto- 

 plasm, which serves also as a stalk to attach it to the muscle 

 fiber. The fibers are usually branched at their ends and 

 so have several points of attachment. 



Parenchyma. — As in other Endoprocta, a definite body cavity 

 is lacking. The space between body-wall and intestinal tract 

 is occupied by the parenchyma, a gelatinous material containing 

 branched anastomosing cells. Through this extend the muscle 

 fibers and within it lie the brain, sexual and excretory organs. 

 A number of rounded or ovoidal highly refractive bodies are 

 found irregularly distributed through the parenchyma. Some 

 of these are represented in PI. XXXIII, Fig. 25. They are 

 found in every part of the animal in which the parenchyma is 

 present. They remain nearly uncolored when treated with 

 carmine stains, and show within a variable number of minute 

 spherical particles which resemble oil globules in optical quali- 

 ties, but do not blacken when treated with osmic solutions. In 

 sections stained by iron-haematoxylin these bodies take an 

 intensely black color, the larger spherical particles showing 

 frequently as lighter spots within. These bodies are often sur- 

 rounded by a clear space, when seen in sections (PI. XXXII, 

 Fig. 16), suggesting the presence of a system of spaces or 

 canals in the parenchyma. In preparations of entire animals, 

 the bodies in question appear arranged in rows or lines forming 

 an anastomosing network, most clearly seen in the expanded 

 lophophore. I believe that it is true that the spaces in the 

 parenchyma form an irregular system of channels through 

 which a body fluid circulates, propelled by the contractions of 

 the animal, and that the rounded bodies described are physi- 

 ologically comparable with blood discs or corpuscles of some 

 higher forms. 



These bodies arise in developing buds chiefly in the axial 

 portion of the stalk. This is composed mainly of elongated cells 

 attached at the upper end to the stomach wall and extending 



