402 INSECT TRANSFORMATIONS. 



these two last facts must be accounted for on other 

 principles, as there is clearly no circulation.^^* 



The statement recently published by one of these 

 authors (Mr. Spence), respecting the alleged dis- 

 covery of insect circulation by Dr. Cams, is founded 

 on facts which were shown and explained to him 

 by the doctor himself. "The first insect," says 

 Mr. Spence, "to which Dr. Carus directed my 

 attention, was the larva of ephemera vulgata (or an 

 allied species), in which, near to the bronchiae and 

 parallel with each side of the body, was very distinctly 

 visible a constant current, towards the tail, of oblong 

 globules swimming in a transparent fluid, propelled 

 w'itli a regular pulsating motion ; and on cutting the 

 body of the larva across near the tail, three globules 

 were most plainly seen pushed out of the divided 

 vessels in a distinct mass, which increased at each 

 pulsation. I cannot express the pleasure which it 

 gave me, to see thus clearly this ocular demonstra- 

 tion of one of the most important physiological dis- 

 coveries of modern times : and my gratification was 

 heightened by the next object which Dr. Carus placed 

 before his microscope, viz. — a specimen of semhlis 

 viridis (the green lace-whiged fly), in which pre- 

 cisely the same phenomena, but, if possible, more 

 clearly, were seen in the nervures of the wdngs and 

 in the antennae, in both which the constant current 

 of globules was most apparent ; and, in the former, 

 the sudden turning of these globules, at the apex of 

 the wing, out of the exterior nervure into a central 

 one, with which it joins and forms an acute angle, 

 was equally curious and striking. On cutting off the 

 end of the antennae, precisely the same emission of 

 globules (which soon assume a greenish tint) took 

 place as in the former case, forming a mass, which 

 was increased with a sudden gush at each pulsation. 

 * Introd. vol. iv. p. 86. 



