LOXOSOMA. 369 



deposition of minute masses, to which the name cell cannot be 

 applied, as they are mere collections of protoplasm, unprovided 

 with any distinct walls, having a waxy appearance and destitute 

 of granules or nuclei. These masses, which must be regarded as 

 accumulations of a homogeneous protoplasm, do not completely 

 fill the cavity ; there remains in the centre a small empty space, 

 which, viewed from above, appears round, but when seen in 

 profile has the form of an elongated hollow. As the bud enlarges 

 this hollow becomes more distinctly defined in the centre of its 

 anterior region, surrounded by the waxy, transparent substance, 

 which takes the form of a heraldic escutcheon. This internal 

 cavity has no connection with the periphery ; it is only at a later 

 stage, after the tentacles have appeared, that it opens out on the 

 circumference to form the central aperture of the tentacular hood. 

 As development proceeds it becomes evident that the primitive 

 fissure in the bud represents the cavity of the hood. Below it 

 three successive accumulations make their appearance, the first 

 large, transverse, similar in appearance to the hood, which is soon 

 hollowed out in the centre, and represents the stomach ; behind 

 this is placed a round, opaque, granulated mass, which may be 

 called the pedal body ; and at the bottom of the bud, near the 

 point of attachment, there is a third, divided into two parts, 

 and with transverse bands alternately granular and transparent — 

 the pedal gland. The spaces between these various organs and 

 the hypoderm are filled with minute granular cells, two of which, 

 situated between the tentacular escutcheon and the stomach, are 

 larger than the rest, and form the rudiments of the reproductive 

 organs. (PI. XXII, fig. 13, n., x, y, and v.) 



The Author differs from Nitsche as to the primitive contents of 

 the bud. The latter considers them to be cellular, the product 

 of a central cell, through continuous division and subdivision. 

 The former believes that the various organs are formed by the 

 differentiation of an undivided sarcodic mass. 



Pursuing the development of the various organs, as soon as 

 the stomach-mass is distinctly defined a triangular figure becomes 

 apparent on the dorsal side of the tentacular escutcheon, extend- 

 ing from the stomach towards the primitive hollow ; it contracts 

 in the middle, enlarging above and below, so as to form two 

 apparently closed cavities, the intestine and the rectum. The 

 walls composing them are of great thickness ; internal cavities 

 are not perceptible from the first appearance of the outlined 

 form. The Author infers that this structure is not formed by 

 the coalescence of cells, but rather by a differentiation of the 

 sarcodic mass that surrounds the primitive cavity. The anal 

 orifice makes its appearance at the last stage, along with the 

 opening of the hood. 



