396 Miscellaneous. 
from a number of observations on various animals, T have been led 
to the conclusion that all vibratile cilia originate in the amorphous 
intercellular substance. In no instance have I ever seen vibratile 
cilia forming direct prolongations of cells, but invariably I find their 
bases imbedded in the intercellular cytoblastema. They may seem 
to be prolonged from the underlying cells; but, on the contrary, as 
I have particularly satisfied myself in regard to the branchize of the 
oyster (Ostrea virginiana), they are based in the cytoblastema, 
which extends in a thin stratum over the outer ends of the cells. In 
other instances they alternate with the cells, projecting in rows be- 
tween them, and forming, as it were, a bristling corona to each cell, 
as I have seen in the epithelium of the intestine of the young Snap- 
ping Turtle (Chelydra serpentina). In the latter instance, when the 
cells are loosed from the intestine, they carry the overlying cyto- 
blastema with them, and consequently, also, the vibratile cilia, which 
then falsely appear like appendages of the cells themselves. The 
nettling cells (enide) of Polypi and Acalephee originate in the same 
substance (the intercellular cytoblastema) as do vibratile cilia. 
They have been supposed to develope within the cells of the layer in 
which they are situated; but this is not true. Oftentimes, when 
cnidz are removed from their basis by pressure, they drag along 
with them a portion of the cytoblastema, which encloses them like 
a transparent envelope, and has the appearance of a cell. Sometimes 
three or four cnidze are pressed out together, and, being covered by 
the accompanying cytoblastema, they present the deceptive appear- 
ance of several cnidee in one cell. 
There are four periods in the history of enidee. Wagner (Wiegm. 
Archiv, 1835) was the first to detect the existence of these bodies ; 
but he mistook them for peculiar forms of spermatozoa of Actinia 
Cereus). Immediately after this, if not at the same date, Ehrenberg 
(Abhandl. Berlin Akad. 1835, Jahrg. [1837] p. 147) recognized 
their true office, and described them as the prehensile organs 
(Fangangeln) of Hydra. Yet in 1842 (Wiegm. Archiv) we find 
him inclined to deny that they have stinging properties, such as 
Wagner attributes to those which he found in Pelagia noctiluca. 
In 1841 (Wiegm. Archiv, p. 38) Wagner described the nettling- 
organs (Nesselorgane) of Pelagia noctiluca; and although he detected 
the spirally-rolled thread in the capsule, and says of the thread, 
“sometimes it appears as if it had a canal,” and figures it so in his 
‘Icones Zootomice’ (1841, pl. 33. fig. 9 B), yet it was reserved for 
Doyere, in the latter part of the next year (Comptes Rendus, Aug. 
1842, p. 429, ‘Note sur quelques poits de l Anatomie des Hydres 
d’Eau douce’’), to describe the mechanism of the cnide, and the 
mode of evolution of the thread, with such completeness as to anti- 
cipate everythmg in this regard that has been published since, up to 
the year 1860, when I figured and briefly pointed out (in Agassiz’s 
‘Contributions,’ vol. ii. pl. 11”, fig. 16°, Aurelia flavidula, and de- 
scription of plate, p. 17, and pl. 11°. fig.5, Coryne mirabilis) an as yet 
undescribed relation of the thread to the cell in which it is coiled up. 
As the brilliant discovery of Doyére has been kept in comparative 
obscurity, at least in America, I will quote from his paper such 
