ANNELIDA TERRICOLA. 



Nevertheless, in addition to all this is found in every segment 

 of the body a pair of membranous vesicles communicating ex- 

 ternally by lateral orifices, apparently analogous to the respi- 

 ratory vesicles of the leech ; and in fact, by many they have 

 been described as constituting the breathing apparatus. Their 

 real office, however, is but imperfectly understood ; they evi- 

 dently have not the same relation with the circulatory system, 

 which the lateral sacculi of the leech are found to exhibit. Are 

 they then merely secreting follicles, destined to furnish a mu- 

 cosity for lubricating the external surface of the body, or are 

 they aquiferous tubes adapted to introduce water into the 

 interior ? Future observations must determine. 



Few points connected with the history of the earth-worm 

 have given rise to so much speculation as the manner of their 

 reproduction. The generative organs have long been known 

 to be lodged in the anterior part of the body, their position 

 being indicated externally by a considerable enlargement or 

 swelling, which extends from the seventh to about the four- 

 teenth segment, counting from that in which the mouth is 

 situated. On opening this portion of the animal, a variable 

 number of white masses are found attached to the sides of the 

 crop and gizzard, which have long by general consent been 

 looked upon as forming the reproductive system. Some have 

 been regarded as representing the testes, others the ovaria : yet 

 so delicate are the connections which unite these glandular 

 masses, and such the difficulty of tracing the ducts 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 gen- 

 erally acknowledged to be hermaphrodite, 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. In the 

 earlier summer months, two of these animals are found to 

 come partially out of the ground from contiguous holes, and, 

 applying together those segments of their bodies in which the 

 generative glands are situated, are observed to remain for a 

 considerable time in contact, joined to each other by a quan- 

 tity of frothy spume, which is poured out in the neighborhood 

 of the sexual organs. No organs of intromission, however, 

 have ever been distinguished ; neither until recently had the 

 canals communicating between the sexual orifices and the tes- 



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