488 THE BLOOD-CORPUSCLES OF THE ANNELIDES. 



' Am einfachsten verhalt sich Branchiobdella mit einem contractilen Ruckengefass 

 und einem in vordern Kbrperstuck durch Schlingen mit dem erstern in Verbindung 

 stehendem Bauchgefasse. Dieses scheint mit der weiten Leibeshohle zu communiciren 

 und aus derselben das Blut zu beziehen welches durch seine contractile Wandung 

 nach vorn getrieben wird.' 



This statement is exactly reproduced at p. 398 of the third edition 

 of Professor Claus's work, which appeared in 1876. 



Similarly, Professor Pagenstecher, at p. 3J3 of his 'Allgemeine 

 Zoologie,' Zweites Theil, 1877, writes : — 



1 Leuckart meint es moge der Ruckenstamm, welcher schon 1719, Dillenius bei den 

 Blutegel beschrieb, mit der bei Branchiobdella unter den Hirudineen besonders weiter 

 Leibeshohle in offener Verbindung stehen, seinen Inhalt aus letzterer beziehen, die in 

 der Leibeshohle auf und abtreibende Fliissigkeit schon Blut sein/ 



As against all these authorities, Professor Lankester himself having 

 made it a question of authorities by his using, ad augendam invidiam, 

 the word ' notoriously/ we have to set his statement, unsupported 

 by any record of independent investigation by himself of the struc- 

 tures themselves, to the effect that the vascular system of Branchiob- 

 della ' notoriously differs ' from that of true leeches, ' in that it most 

 certainly does not communicate with the perivisceral cavity so as to 

 form a lacunar circulation.' 



I have fastened upon Professor Lankester's employment of the 

 word ' notoriously,' and I think that what I have said will ' suffice to 

 satisfy a conscientious bookmaker/ or book-reader, as to the value 

 of the word as thus employed. 



The question of fact is very readily stated, and if not very easily 

 settled is yet capable of settlement by persons to whom Branchiob- 

 dellae are available in the fresh state. It may be put thus : Does 

 the simple unicavitary large perivisceral space of Branchiobdella, the 

 bomologue of the lymphatic system in general, and of that parti- 

 cular vasiform tri truncate modification of it which is found in so many 

 leeches, differ from the lymphatic system or its homologue in nearly 

 all other animals, if not all, with the exception of the Chaetopho- 

 rous Vermes, by not communicating with the blood- vascular system ? 

 I never thought that in the Hirudineae, provided, as is ' notoriously ' 

 the case in Hirudo sanguisuga (Gratiolet, 'Ann. Sci. Nat.' xvii. 

 p. 199, 1862) and in Piscicola (see Budge in 'Verhand. Nat. Verein. 

 Preuss-Rheinland,' vi. p. 112, and fig. 24, 1840, and Leuckart, I.e. 

 p. 669), with a system either of smaller or larger tubes, bringing 

 these vasiform specialisations of the perivisceral cavity continuously 



