KEPKODUCTION BY MECHANICAL SECTION. 



239 



Careful experiments, made to ascertain how far the statements of former 

 authors upon this subject might be substantiated,, prove that the assertion 

 is not entirely without foundation, al- 

 though by no means to the extent indi- 

 cated in their writings. It would, indeed, 

 be easily credited that the removal of the 

 hinder part of the body of an Earthworm 

 would not necessarily destroy the anterior 

 portion, since no organs absolutely essen- 

 tial to existence are removed by the opera- 

 tion, and even the course of the circulating 

 fluids would not be materially inter- 

 rupted by the mutilation ; but that the 

 hinder moiety should be able to repro- 

 duce the mouth, gizzard, and stomach, 

 the complicated apparatus of moniliform 

 vessels, and the sexual organs, contained 

 in the anterior segments, could scarcely 

 be deemed possible ; and the assertion has 

 been satisfactorily disproved by actual ob- 

 servation. On cutting an Earthworm in 

 two, the anterior portion is found, in fact, 

 generally to survive; and the wound 

 caused by the operation, becoming gradu- 

 ally constricted, is soon converted into an 

 anal orifice, rendering the animal again complete in all parts necessary 

 for its existence. This, however, is by no means the case with the 

 posterior portion ; for, although it will exhibit for a very long period 

 indications of vitality, no signs of reproduction have been witnessed, 

 and it invariably perishes. 



(627.) Nevertheless, although it is thus proved that the Earthworm 

 cannot be multiplied by mechanical division, it is stated to be able to 

 reproduce small portions of its body the removal of which does not im- 

 plicate organs essential to life. In the experiments of M. Duges, for 

 example, it was found that four, or even eight of the anterior rings 

 might be cut off with impunity, although the cephalic pair of ganglia, 

 the mouth, and a part of the oesophagus were necessarily taken away. 

 In worms thus mutilated, after the lapse of from ten to thirty days a 

 conical vascular protuberance was observed to sprout from the bottom 

 of the wound ; and in eight or ten days later this new part had become 

 so far developed, that not only all the lost rings were apparent, but 

 even the upper lip and mouth had assumed their normal form, and the 

 animal again began to eat and bury itself in the earth. 



(628.) The experiment of artificially bisecting the body of an Earth- 

 worm, replacing the divided halves with care again in their native 



Eggs of the Earthworm. 



