234 



ANNELIDA. 



white masses are found, attached to the sides of the crop and gizzard 

 (fig. lll,7t^7i) ; these have long, by general consent, been looked upon 

 as forming the reproductive system some having been regarded as 

 representing the testes, others the ovaria : yet so delicate are the con- 

 nexions which unite these glandular masses, 

 and such the difficulty of tracing the ducts Fig. 113. 



whereby they communicate with the exterior 

 of the body, that the functions to which they 

 are individually appropriated have given rise 

 to much discussion. The Lumbrici have 

 been generally acknowledged to be herma- 

 phrodite, that is, possessed of organs adapted 

 both to the formation and fertilization of 

 ova ; and it is likewise well understood that 

 the congress of two individuals is essential 

 to the fecundity of both, as, in the earlier 

 summer months, the mode in which they 

 copulate is a matter of constant observation. 

 At such times two of these animals are found 

 to come partially out of the ground from con- 

 tiguous holes, and, applying together those 

 segments of their bodies in which the gene- 

 rative glands are situated, are observed to 

 remain for a considerable time in contact, 

 joined to each other by a quantity of frothy 

 spume which is poured out in the neighbour- 

 hood of the sexual swellings. No organs of 

 intromission, however, have ever been di- 

 stinguished ; neither, until recently, had the 

 canals communicating between the sexual 

 orifices and the testicular or ovarian masses 

 been satisfactorily traced ; so that Sir 



Everard Home* was induced to believe that, in the kind of intercourse 

 above alluded to, there was no transmission of impregnating fluid from 

 one animal to the other, but that the excitement produced by mutual con- 

 tact caused both the ovaria and testes to burst, so that the ova escaping 

 into the cells of the body became there mingled with the spermatic 

 secretion, and being thus fertilized, were hatched internally, and the 

 young, having been retained for some time in the cells between the in- 

 testine and the skin, were ultimately ejected through apertures supposed 

 to exist in the vicinity of the tail. 



(609.) According to M. Dugesf, the arrangement of the sexual parts 

 is represented in the diagram, fig. 114. The testicles (>) are placed 

 in successive segments of the body from the seventh backwards ; they 

 * Lectures on Comp. Auat. vol. iii. f Ann. des Sci. Nat. vol. xv. 



Plan of the circulation in an 

 Earthworm. (After Dr. Williams.) 



