496 THE BLOOD-CORPUSCLES OF THE ANNELIDES. 



fig", i, G) from the still living blood-vessels of one of the Opheliae 

 which in some other respects resembles the Oligochaeta. . 



A more instructive confirmation of the view which regards the 

 minute granules in human blood, known as Zimmermann's bodies, 

 if not those figured by Schultze (' Archiv Mikr. Anat.' pi. i.) as 

 being, in opposition to the views of Zimmermann himself, to whom 

 we owe so much of our right views as to fibrin, mere ' Detritus- 

 bildungen,' I cannot conceive than that which is furnished by the 

 watching of the falling to pieces of the lumbricoid corpuscles under 

 the disturbing action of the addition of water, or, though to a less 

 degree, under that of the transference from a glass vessel such as 

 the capillary pipette to the wider contact of glass constituted by 

 the slide and cover 1 . 



It is possibly even more interesting to remark how closely 

 parallel is the behaviour of alumina, and some other inorganic 

 substances, to that of the sanguigenous colloids which we are 

 dealing with ; ' soluble alumina,' says Professor Graham (' Phil. 

 Trans.' 1861, p. 207), ' is one of the most unstable of substances — 

 a .circumstance which fully accounts for the difficulty of preparing 

 it in a state of purity. It is coagulated or pectized by portions 

 so minute as to be scarcely appreciable of sulphate of potash, and, 

 I believe, by all other salts, and also by ammonia. A solution 



1 Since writing as above, I came, by following up a reference ofVirchow's ('Cell. 

 Path.' ed. 1871, p. 240), upon the following passage (Virchow's 'Archiv,' i. p. 389), 

 in which that observer, in describing the separation of the coloured elements from the 

 rest of the blood-corpuscles, writes as follows : — ' Sowohl bei dieser Entwickelungs- 

 weise, als da, wo das Hamatin zuerst an Faserstoffgerinnsel, etc., getreten war, sieht 

 man in dem Maasse, als die Kbrner scharfer hervortreten, am Rande eine farblose 

 Substanz erscheinen, die nicht selten, ahnlich einer Zellenmembran, die Korner 

 umschliesst. Indess habe ich mich nie uberzeugen konnen, dass dieser Saum etwas 

 anderes, als eine homogene Substanz sei ; er zeigt keine der Eigenschaften, welche als 

 Kriterien fur eine permeable, vom Zelleninhalt trennbare Membran gelten durfen, 

 und ich muss daher Gluge beistimmen, wenn er sagt (' Atlas der Pathol. Anat.' Lief, 

 iii. Melanose, p. 4) : "Oft werden die unregelmassigen oder viereckigen schwarzen 

 Massen nur von einer membranosen TJnterlage (die wahrscheinlich durch coagulirten 

 Faserstoff gebildet ist) zusammengehalten, und als dann erscheint eine dxinne Lamelle 

 unter dem Mikroskop, wie Schildplatt." ' Remak, in his ' Entwickelung der Wirbel- 

 thiere' (1855, p. 22-23), gave a similar explanation of the nature of the so-called 

 • Blut-inseln,' speaking of them as ' Zufallige Anhaufungen von Blutzellen welche 

 durch geronnen Faserstoff zusammengehalten und eingehullt sind.' 1 incline, how- 

 ever, to think that the concentric striation observable round the pigment nodules 

 above mentioned may be due to the rearrangement of the ' oecoid ' after the central 

 concentration of the ' zooid,' which is then surrounded by it much as a rocky islet 

 may be seen at low water to be surrounded by a zone of smooth sand. 



