Respiration in Invertebrate Animals. 335 



channels destined to contain a real chylaqueous Huid with a 

 system of true blood-vessels. M. Blanchard's inferences are 

 drawn from injected specimens. In such investigations the me- 

 thod of injection is liable to numerous fallacies ; it imparts a 

 uniform diameter to canals which are remarkable for variety of 

 calibre. The real chai-acters of such structures can only be de- 

 termined by direct inspection of the living individual. Thus 

 only can the fact be demonstrated, that the so-called blood-vessels 

 of the parenchymatous worms neither rythmically contract nor 



qu'il existe la un veritable reseau vaseulaire." In principle how totally 

 this definition ditfers from the former I 



Bojanus and Nordmann have described almost in the same words the 

 same system, indicating it as the apparatus for the circulation of the 

 blood-proper. In relation to the Cestoid worms M. E. Blanchard observes : 

 " Pendant longtemps, partageant I'erreur commune, je pensais qu'il n'ex- 

 istait point de systeme vaseulaire proprement dit chez les Cestoides. Les 

 canaux gastriques, communiquant de I'un a I'autre dans chaque Zoonite, 

 etaient regardes tres-generalement comme destines a remplir les fonctions 

 des deux appareils. Mais recemment, dans les Ttenias du chien et de la 

 fouine, j'ai constate, indejiendamment de ces canaux gastriques on intes- 

 tinaux, I'existence d'un sjsteme vaseulaire tres-complexe, consistant en 

 vaisseaux longitudinaux pourvus de ramifications et d' anastomoses nom- 

 breuses. Ainsi ces animaux remarquables, consideres par les zoologistes 

 les plus eminents comme des Vers parenchymateua: completeraent degrades, 

 sont au contraire des etres dont I'organisation est loin d'etre tres-simple." 

 (Annales des Sciences, tome viii. 1847, p- 119.) 



In the Cestoid worms M. Blanchard describes a perfect blood-vascular 

 system, independently of that of the straight lateral canals which consti- 

 tute the gastric apparatus. He describes an artery, a vein, and an inter- 

 mediate order of straight parallel capillary vessels. In the Trematoda, in 

 one place he states that the extreme vessels form a ramifying plexus ; in 

 another he remarks, " II est a remarquer aussi que les vaisseaux de la 

 partie anterieiu-e (speaking of the vessels in Amphistoma conicum (Regne 

 Animal, pi. 28)'), et surtout ceux de la partie posterieure du corps, se ter- 

 minent sous la peau en de petites lacunes, du reste tres-nettement circon- 

 scrites." No instance is known in the whole animal kingdom of a blood 

 system terminating in caecal extremities. The apparatus which exhibits 

 such characters cannot fall under the denomination of a blood-projier 

 system. The method of investigation adopted by M. Blanchard has dis- 

 torted the features of the object sought to be studied. Forcible injections 

 into textures fragile and dehcate will enable a preoccupied fancy to con- 

 struct any results, to recognise grounds for any conclusion. The views 

 stated in the text are founded upon examinations conducted with extreme 

 care, and instituted on living specimens. To a great extent the author's 

 researches have corroborated the descriptive anatomy of il. Blanchard : in 

 many essential respects however they stand in direct op|X)sition. If the 

 system of vessels depicted in the figures of M. Blanchard were really a true 

 blood system, the Cestoid and Trematoid Entozoa would be entitled to 

 rank high in the zoological scale. They stand really below the AnneUda. 

 To this position they are assigned on the ground of the general affinities of 

 their organization. The author is persuaded that the French helmintho- 

 logist has mistaken a modified chylaqueous system for a blood-proj)er ap- 

 paratus. 



