190 Dr. T. Williams on the Mechanism of Aquatic 



tion. But his conclusions have by no means received the un- 

 divided assent of subsequent observers*. It is easy to prove 

 that the coverings of the tracheae are very unlike those im- 

 plied in the inferences of M. Blanchard. This will be after- 

 wards done. 



Agassizf declares that he has repeated the injections of M. 

 Blanchard with confirmatory results. At this period M. Charles 

 Bassi and M. FilippiJ undertook especially to examine this 

 question. They fed the larva of Sphinx atropos and Bombi/x 

 mori on indigo, cochineal and other coloured substances ; they 

 found on dissection that the trachese were everywhere coloured ; 

 they satisfied themselves that the colour was limited to the tunics 

 of the aeriferous tubes ; it never entered into the interior. Prof. 

 Alessandrini §, varying the preceding observations, concludes 

 from similar experiments that the coloured matter actually 

 enters into the interior of the tracheal tube : — " Le Prof. Ales- 

 sandrini crut remarquer que la matiere coloree etait contenue 

 dans Pinterieur meme des trachees, et que la coloration depen- 

 dait ainsi d^une veritable injection de vaisseaux tracheens." 

 The famed observations of Mr. Bowerbank lend support to the 

 views of the French and Italian observers just explained. He 

 remarks, " the course of the blood is almost invariably in imme- 

 diate connexion with that of the trachese." Mr. Newport, in 

 his article " Insecta,"" teaches precisely the same doctrine. In a 

 paper very recently || read before the Linnsean Society on the Ich- 

 neumon atropos, Mr. Newport statesj "that the ramifications of the 

 trachese which penetrate the structure of the alimentary canal and 

 of every other organ, become denuded of their external covering, 

 and then seem to form only two tissues, the spiral and the 

 mucous ; if indeed there be not also, as he has some reason to 

 think, an extremely delicate serous or basement, closely adherent 

 to and uniting the coils of the fibrous tissue on its external 



* With reference to the remarkable relation which, according to M. 

 Blanchard, subsists between the tracheae and the blood, it is important that 

 his views should be clearly apprehended. He says again, — " Mais n'est- 

 ce pas plus encore sous le rapport de la nutrition que ces tubes respi- 

 ratoires, dont nous connaissons la nature actuellement, doivent arreter notre 

 attention. En portant de I'air dans leur interieur ils portent le sang dans 

 leur peripheric. Ces trachees divisees et ramifiees a I'infini dans la pro- 

 fondeur de I'economie conduisent ainsi le fluide nourricier a tous les organes, 

 a tous les muscles au moment meme, oil il vient de subir le contact de I'air. 

 C'est le sang nouvellement arterialise, le sang propre a vivifier, k nourrir 

 tous les organes." — Op. cit. p. 380. 



t Annal. des Sc. Nat. 1851, and Proceedings of the American Asso- 

 ciation for the Advancement of Science, Cambridge, U.S., &c. 



X Ann. des Sc. Nat. 1851. 



§ At the Scientific Congress held at Geneva, Sept. 1851. 



II See Annals and Magazine of Nat. Hist, for July 1853. 



