THE METAMORPHOSIS. 427 



production. Beckmann * and Goeze t have imparted experiments, the 

 results of which are that the former, in Agrion virgo, and the latter in 

 Semblis bicaudala, Fab. (Perla, Geoff.), once observed a leg, which 

 was smaller than the rest, whence Goeze concludes that this leg must 

 have been lost, and subsequently replaced by a new one. To these 

 former observations we may add some more recent ones of Heineke |, 

 which are absolutely of greater importance. On the 25th of July he 

 cut off both the antenna? of a Blatta Madeiras, after which it moulted 

 on the 8th of August, and now acquired two new, but much shorter 

 ones. He repeated the same experiment in the pupa of a Reduvius, 

 where he obtained the same result. In perfect insects also, subject to 

 no further moulting, namely, species of the genera Forjicula, Gryllus, 

 Locmta, and Acridium, he mutilated in the same manner, but even in 

 the space of two months they acquired no new limbs, but cast off the 

 old ones shortly after they were injured. These results entirely har- 

 monise with the reproduction of the spiders ; these also renew their 

 lost limbs only so long as they yet moult, whereas after their last 

 moulting they cast off their mutilated ones, but acquire no new ones. 

 We must, therefore, ascribe to insects, at least to those with an imperfect 

 metamorphosis, the power of replacing lost limbs, with these restric- 

 tions. It does not appear to be different in insects Avith a perfect 

 metamorphosis, for mutilated caterpillars are said to obtain new limbs, 

 that is to say, legs, after the next moulting. But it is remarkable that 

 these limbs do not germinate whilst the insect remains in its old case. 

 I think this circumstance is explained by the hardening of the integu- 

 ment, whence it is to be considered as it were dead, and thence I deduce 

 the reason of the known fact, that wounds given to insects cicatrise 

 only upon the next moulting, and consequently never in their perfect 

 state. It must also be attributed in a great measure to the deficiency 

 of blood vessels, for by their assistance cicatrisation and the resupply 

 of flesh is promoted, namely, the constant streaming of the blood to 

 the wounded spot, is the first cause of its subsequent living recon- 

 nexion. By means of the blood the lips of the wound are stuck 

 together, and hence is formed the cellular tissue which unites the 

 divided parts. Both blood and cellular tissue are consequently the 

 means which nature makes use of to replace lost or divided animal 



" Physinkalisch-cekonomische Bibliothek. vol. viii. p. 20. 



f- Naturforscher, part xii. p. 221. 



I Isis, 1801, p. 1359. From the Zoological Journal, vol. iv. p. 422. 



