iS61.] DR. T. S. COBBOLD ON CYSTIC ENTOZOA. 96 



display evidences of concentric lamination, the rings resembling 

 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 xoVu^^' ^^^ ^ breadth of from ^-j/y^y to ^/„„th of an inch. On 

 the addition of diluted sulphuric acid, a rapid effervescence took place, 

 accompanied with the total destruction of the corpuscles ; whereas 

 the alkaline reagent liquor potassse caused only a gradual disso- 

 lution of the enveloping membrane, leaving behind a perfectly trans- 

 parent and thin calcareous plate, unpossessed of any appreciable 

 light-refracting properties. The last-mentioned change proceeded 

 uniformly from without inwards; the corpuscle marked/ (fig. 5) 

 presenting at intervals appearances precisely like those indicated at 

 ff, h, i, k, 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. 



I have not detected any appearance of subdermal pouches, such as 

 those discovered and described by me elsewhere as occurring in the 

 immature Tricuspidaria nodulosa * ; but I have carefully noted the 

 foregoing particulars because the definitive solution of several inter- 

 esting questions depends upon a correct appreciation of the relative 

 structure, chemical constitution, and disposition of the calcareous 

 corpuscles as observed in the various groups of Entozoa in which 

 they are known to abound. 



From recent investigations, and more especially from those of 

 Claparede, I think we may inferentially draw the following conclu- 

 sions : — 



These bodies cannot be regarded in the light of pathological pro- 

 ducts, as Moulinie and others suppose ; and it is still more obvious 

 that Tschudi, Gulliver, Goeze, and Zeder were wrong in describing 

 them as eggs. Eschricht, and the late Prof. 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 func- 

 tion analogous to that of the blood- and lymph-corpuscles, and the 

 latter described them as " assimilating cellules." Prof. A^an Beneden 

 is probably also as incorrect in viewing them as cutaneous glands 

 " secreting a mucus destined to lubricate the surface of the body." 



To offer a true explanation of their character and purpose is still, 

 however, a matter of great difficulty ; for there seems to be no doubt 

 that in some instances, especially in mature cestodes and in certain 

 trematodes, the presence of carbonate of lime is contra-indicated. 

 The circumstance also of Claparede's having discovered these bodies 

 to be included within dilatations or ceecal pouches connected with 

 the excretory system of Holosiomata, considered in association with 

 the fact that I have myself found them lodged in peculiar oviform 

 sacs in Tricusjridaria (Tricenojj/tortts) , woidd likewise seem to forbid 

 our acceptance of Von Siebold's notion, that the bodies in question 

 are comp.irable with the " spicules and calcareous networks " 

 strengthening the integument of Echinoderms. Neither can I, in 



* Quart. Journ. of Microscopical Science, vol. vii. pp. 115, 202. 



