Chap. XXVII. OF PANGENESIS. 357 



found that, out of about 58,000 eggs laid by unimpregnated 

 silk-ruoths, many passed through their early embryonic 

 stages, showing that they were capable of self-development, 

 but only twenty-nine out of the whole number produced 

 caterpillars. The same principle of quantity seems to hold 

 good even in artificial fissiparous reproduction, for Haeckel 17 

 found that by cutting the segmented and fertilised ova or 

 larvaa of Siphonophone (jelly-fishes) into pieces, the smaller 

 the pieces were, the slower was the rate of development, and 

 the larva* thus produced were by so much the more imperfect 

 and inclined to monstrosity. It seems, therefore, probable 

 that with the separate sexual elements deficient quantity 

 of formative matter is the main cause of their not having 

 the capacity for prolonged existence and development, unless 

 they combine and thus increase each other's bulk. The belief 

 that it is the function of the spermatozoa to communicate 

 life to the ovule seems a strange one, seeing that the un- 

 impregnated ovule is already alive and generally undergoes a 

 certain amount of independent development. Sexual and 

 asexual reproduction are thus seen not to differ essentially ; 

 and we have already shown that asexual reproduction, the 

 power of re-growth and development are all parts of one and 

 the same great law. 



Re-growth of amputated parts. — This subject deserves a little 

 further discussion. A multitude of the lower animals and 

 some vertebrates possess this wonderful power. For instance, 

 Spallanzani cut off the legs and tail of the same salamander six 

 times successively, and Bonnet, 18 did so eight times; and on 

 each occasion the limbs were reproduced on the exact line oi 

 amputation, with no part deficient or in excess. An allied 

 animal, the axolotl, had a limb bitten off, which was re- 

 produced in an abnormal condition, but when this was 



less vitality " than those from ferti- 18 Spallanzani, 'An Essay on Animal 



lised eggs. In the third partheno- Reproduction,' translated by Dr. 



genetic generation not a single egg Maty, 1769, p. 79." Bonnet, '(Euvres 



yielded a caterpillar. d'Hist. Nat.,' torn, v., part i., 4 to. 



17 ' Entwickelungsgeschichte der edit., 1781, pp. 343, 350. 

 Siphonophora,' 1869, p. 73. 



