T^NIA MABGINATA. 251 



were even more numerous than has been indicated in the accom- 

 panying drawing (fig. 55), but their relative disposition and size are 

 accurately represented. Their form is commonly that of spherical 

 or oval, flattened disks (fig. 55, /, c, e) ; but not unfrequently they 

 are elongated, occasionally thicker at one end than the other {a, d), 

 and sometimes reniform (b). All are bordered by an opaque 

 margin ; and they often display evidences of concentric lamination, 

 the rings resembhng nuclei and nucleoli (e). In respect of size, 

 they do not, for the most part, at least, vary materially ; they have 

 an average length of j^" to j^", and a breadth of from 2^ to i^ of 

 an inch. On the addition of diluted sulphuric acid, a rapid efier- 

 vescence took place, accompanied with the total destruction of the 

 corpuscles ; whereas the alkaline reagent liquor potass£e caused 

 only a gradual dissolution of the enveloping membrane, leaving 

 merely a perfectly transparent and thin calcareous plate, unpos- 

 sessed of any appreciable hght-refracting properties. The change, 

 just mentioned, proceeded uniformly from without inwards ; the 

 corpuscle marked / (fig. 55) presenting, at intervals, appearances 

 precisely hke those indicated at g, h, i. It, I, and m. The last is 

 the isolated calcareous plate, whose circumferential border has lost 

 that entire smooth outhne which the unaltered corpuscle invariably 

 exhibits. 



From recent investigations, and more especially from those of 

 Claparede, I think we may inferentiaUy draw the following con- 

 clusions : — 



These bodies cannot be regarded in the hght of pathological 

 products, as Mouhnie and others suppose ; and it is still more 

 obvious that Tschudi, GuUiver, Groeze, and Zeder were wrong in 

 describing them as eggs. Bschricht, and the late Professor 

 William Smith of Cork, clearly erred in attributing to them a 

 special nutritive function, when the former spoke of them as 

 " elementary granules " having a function analogous to that of 

 the blood and lymph-corpuscles, and the latter described them as 

 "assimilating cellules." Professor Van Beneden is probably also 



