ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
601 
The function of this cell is to prevent the stomach moving too far 
towards the head of the animal, on the contraction of the muscles of the 
oesophagus. 
The vibratile flame of the terminal organ of the nephridial apparatus 
is covered with longitudinal striae, each of which begins by a small 
thickening ; as a consequence of this the base of the flame is bounded 
by a row of small dots. In the living animal the vibratile flame and 
its filaments exhibit a continuous undulatory movement, which moves in 
a centripetal direction. The author thinks that the filaments serve 
merely to make the organ firmer, and that one of them, more powerful 
than the rest, is the seat of a movement analogous to that of the vibratile 
flame, and is perhaps destined to aid the movement of the fluid of the 
general cavity from the body towards the kidney. There is no valve 
at the opening of the duct into the bladder ; it is possible that the 
numerous folds of the nephridial tube are sufficient to stop the reflux of 
the fluids. 
The large, spherical bladder contracts ten times a minute ; its wall 
is formed by large, very flat cells ; in addition to these there are two 
large stellate cells with numerous prolongations which cover the whole 
of the bladder with a contractile plexus. 
The winter eggs are covered with three membranes ; a delicate 
internal membrane, most clearly visible when it becomes folded, owing 
to some alteration in the egg ; the next membrane is very thick, striated 
and divided into two concentric zones; the striation is due to a number 
of fine canaliculi, radially arranged ; they are thickened towards the 
interior, and it is these thickenings that give the appearance of a division 
of the membrane into two zones. The outermost membrane is homo- 
geneous and yellowish. 
The male efferent duct is remarkable for its enormous diameter ; 
this is related to the presence of a large spermatophore. This last is of 
a yellowish-brown colour, and is formed by the union of a large number 
of chitinous elements, polyhedral in form and varying in size. The 
contained cavity is circular, but eccentric in position. As a canal 
which contains a spermatophore loses its glandular appearance, we may 
suppose that the product of its secretion has been used in the formation 
of the spermatophore. 
In a somewhat shorter notice on Lacinularia, M. Masius calls atten- 
tion to some groups of cells which form organs the significance of which 
is not as yet understood. At the sides of the dorsal part of the salivary 
glands there are two rows of cells which, converge towards the medio- 
dorsal line. In the place of the posterior extremity of the vitellogenous 
gland, placed very superficially, there are always to be seen two small 
rows of cells which trend backwards and nearly meet in the medio- 
ventral line. These cells appear to have no relation to the adjoining 
organs. On the ventral surface there is a mass of multinucleate proto- 
plasm without any visible cell-boundaries ; the nuclei are arranged 
symmetrically, in fives. 
Anatomy of Rotifers.* — Mr. R. Vallentin has made serial sections 
of Melicerta ringens , M. conifera, Brachionus rubcns , and Lacinularia 
* Ann. and Mag. Nat. Hist., viii. (1891) pp. 34-47 (2 pis.). 
