274 DR A. J. WHITING ON THE 



to notice the peripheral blood-sinus, and consequently, as we think, falls into error 

 of observation in some correlated points. He states,* for example, that the network 

 of the ellipsoids is continuous with that of the pulp, while, as a matter of fact, the 

 two are separated by a blood-sinus and a special envelope. He notices t the fine 

 canals unlined by endothelium in the substance of the ellipsoid, but thinks that they 

 all terminate in the meshes of the reticulum, while we believe that most of them, if 

 not all, after anastomosing with each other, open into the peripheral blood-sinus. 

 He is able to state positively! that the concentrically arranged nuclei are those of 

 muscle fibres. To Kyber § belongs the credit of observing the presence of blood- 

 channels at the periphery of the ellipsoids ; he, however, did not recognise that they 

 were cavities or sinuses, but looked upon them as capillary veins. Klein, || differing 

 from all authors, considers that the axial vessel of the ellipsoid is not a capillary but 

 a minute artery, and as regards several animals we are able to confirm his observation. 

 W. Muller H describes the termination of a nerve fibre in an ellipsoid, but this single 

 observation has never been confirmed. 



Many different views as to the significance of the ellipsoids have been advanced; 

 Billroth ** thinks they correspond with the adenoid sheath of the Amphibia; Schweigger- 

 Seidel tt that they serve to filter the blood ; Kyber JJ that they are merely local swellings 

 of the arterial sheath ; and Bannwarth §§ looks upon them as foci for the transformation 

 of the tissue of the arterial sheath into pulp tissue, and that they serve to narrow the 

 blood stream. We can agree in some measure with all of these views, except the 

 former part of the last, for we think that they are the representative of the adenoid 

 sheath, and they are swellings of the tissue of the arterial sheath, and also that they 

 ma) 7 filter the blood by allowing the blood plasma to escape through the minute 

 capillary channels into the peripheral sinus while the corpuscular elements of the 

 blood are retained in the axial vessel. But we also think that they may be relics 

 of the continuous ellipsoidal sheath of the lower vertebrates, and would suggest that 

 they may subserve the function both of contractile bodies on the course of the main 

 vessel, and of expansile bodies within capacious blood chambers ; that they may serve 

 to minimise the effect of the pulse wave, transmitting the blood more gradually from 

 the relatively very large arteries to the thin-walled blood spaces of the pulp, to empty 

 at the same time by their expansion the peripheral blood-sinus, and by their contraction 

 to help the flow of blood through the emergent veins. 



Summary regarding the Ellipsoidal Sheath and the Splenic Ellipsoids. 



1. The terminal portion of the splenic arteries in the Teleostean fish, in the tortoise, 

 and in the hawk is invested by a continuous ellipsoidal sheath, which consists of a homo- 

 geneous ground substance containing a few lymphoid cells. 



* Bannwarth (26), p. 403. t Bannwarth (26), p. 415. J Bannwarth (26), p. 404. § Kyber (13), p. 562. 

 || Klein (17), p. 426. 1 W. Muller (12), p. 360. ** Billroth (8), p. 97. 



tt Schweigger-Seidel (10), p. 971. %% Kyber (13), p. 562. §§ Bannwarth (26), p. 431. 



