228 KD1TOR ON CIRCULATION IN INSECTS. 



insect," he says, " to which Dr. Cams 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 swim- 

 ming in a transparent fluid, propelled with 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 demonstration 

 of one of the most important physiological discoveries of modern times." 

 These are almost the very terms used in the Examiner newspaper, 14th 

 April, 1833, respecting another alleged discovery of the circulation in 

 insects, claimed for James Bowerbank, Esq. F. G. and Z. S., but who 

 has not, so far as I am aware, made any such claim himself. The details 

 of this newest discovery, however, amount to no more than those of Com- 

 paretti in 1800, of Carus in 1824, and of Straus-Diirckheim in 1829, 

 and relate chiefly to the grub of an Ephemera, as do those of Compa- 

 retti and Carus. It is particularly worth remarking that Mr. Bower- 

 bank expressly says that " the blood does not appear to be confined 

 within any specific vessels," before it passes into the dorsal vessel; 

 which is unquestionably correct, as most naturalists have expressed the 

 same opinion, from Lyonnet downwards ; but it at the same time proves 

 that there cannot be any direct circulation. 



It may be worth quoting from Goring and Pritchard's Natural His- 

 tory of Living Objects, published February, 1829, a passage respecting 

 the circulation in the grub in question, particularly as it certainly con- 

 tains a discovery, though this has not, I believe, been claimed as such. 



" During the infant state," it is remarked, " of this larva's existence 

 it is very transparent, exhibiting, under the microscope, in a most sur- 

 prising manner, the circulation of the blood along the large arteries in 

 the body, legs, and tail. While traversing the tail, the blood resem- 

 bles a string of globules. The part which exhibits the most rapid cir- 

 culation is the lower lip. The passage of the blood through the head 

 has a very singular appearance. It runs through a vessel which passes 

 quite round the body of the larva, constituting a band, which, incur- 

 vating itself on the head, forms, as it were, a semicircular chain round 

 the base of each antenna.'' 



The celebrated Goethe has well remarked, that " the number of real 

 discoveries is small, especially when one views them consecutively 

 through a few centuries ; yet people are very busy in repeating what 

 has been discovered by others." Viewing the alleged discovery above 



