Chap. III. GENUS PLEUROBRACIIIA. 2.39 



and see tliem by themselves, a very flat field is required. With such an ol)jective 

 the field acts like a section upon the walls and contents of the vesicle, and the 

 granular coating can be brought into strict profile [Fif/s. 2 and 7/) and displayed 

 as a single layer upon the outside of the wall of the cell, whilst the interior 

 surface of the same wall is proved to be lined by the spirally coiled lasso-thread 

 {Fig. 2 Jj c d). The surface of attachment must be very small, or else the granular 

 covering prevails as much on that side as elsewhere : at any rate, we always find 

 the whole cell, when loosened, covered by these granules. 



The first feature that strikes the eye when investigating the interior of these 

 lasso-cells is the total absence of the axial, rod-like body, so commonly observed 

 in all other lasso-cells (see PI. XIX. Fig. 5 h V) : the whole middle portion appears 

 totally void, and such is the true state of things, for the coil always presses 

 closely against the inner surface of the wall, as long as it is in a quiescent .state. 

 The wall has one uniform thickness throughout, excepting at one point, corresponding 

 to one of the ends of the coiled thread, and there it thickens and forms a broad, 

 conical basis, with which the lasso is continuous, the one gradually passing into 

 the other {Fig. 2 c). Although the thread arises from the wall very obliquely, 

 it is not attached by one side, but at the extreme tip, and suddenly bends upon 

 itself to follow its spiral course. When partially uncoiled {Fig. 8), this sharp bend 

 {c) may be more plainly seen ; but when it is straightened out {Figs. 3, 4, 5, 10 c) 

 the bend disappears, and the thread meets the wall at right angles. In this state 

 the broadened base is a marked feature. Eeturning to the uncoiled lasso again 

 {Fig. 2), we will observe that the coils {h) are set very far apart, but at equal 

 distances, and do not make more than seven or eight turns before the thread 

 terminates very abruptly, at a point {d) directly opposite to the basis of attach- 

 ment (c) ; but the end is perfectly free from the wall against which it presses. 

 Another noticeable feature in the thread is, that it is as easily seen at one part 

 as at any other ; and this is owing to the fact, that it has one uniform thickness 

 from the base to the tip. This, when compared to the gracefully tapering lassos 

 of Discophorte (PI. XV. and XIX. Fig. 5"), appears very clumsy, and looks as if it 

 might be rather inefficient ; yet nowhere do we find lassos so tenacious of their 

 hold as among the Ctenophora) : and this is all the more remarkable because, in 

 addition to the shortness of the thread, which is only eight or nine times longer 

 than the diameter of the cell, it is perfectly smooth, and also blunt at the tip. 



With this amount of knowledge of the lasso-cell, one might very naturally suppose 

 that the lasso makes its exit from the cell as all other lassos among Discophoras 



up within the cell, and knew nofhinjr of the pe- the vesicle ; and both mistook the granuhir bodies 

 culiar mode of connection between the thread and to be icilh'n tlie cells, instead of without. 



