Mr. II. C. Williamson on a Bijid Earthworm. 22."3 



would in that case be the right and left walls of the original 

 intestine. Two new rows of nephridia would be produced, 

 one on the inner side of each appendage. The secondarily 

 formed organs would probably differ slightly in structure 

 from the corresponding original organs. Xo difference was 

 noticed between the ne|diridia of one row and the nephridia 

 of any of the other three rows in the appendages. Again, 

 it would naturally be expected that the appendages would 

 be symmetrically joined to the anterior trunk. This, 

 however, is not the case. Lastly, the dorsal line, whicii 

 is absent in the right appendage, would probably have 

 been present in both appendages had this been a case of 

 median fission. If the fission were supposed to have taken 

 place a little to one side of the median line greater difficulties 

 would be encountered. This is, then, apparently a ease of 

 budding, not of bifurcation. The right-hand appendage is a 

 bud of segment 54, probably formed subsequently to the 

 complete development of the original worm. Tlie original 

 worm is represented by ADB (fig. 1), and the right-hand 

 appendage U'C (fig. 1) is an outgrowth from the right 

 side of the somite and away from the middle line. The 

 growth in diameter of the bud has caused the increase in size 

 of the right side of the somite. 



The third view is that the bifurcation may be the result of 

 lateral budding. In many annelids longitudinal budding is 

 common, and in the ISyllidas lateral budding also regularly 

 takes place. These buds give rise to new individuals. It is 

 impossible to tell whether the bud under consideration might 

 have given rise to a new individual, or whether, like the bud 

 described by Bell, it might have been absorbed if the Lum- 

 hricus had lived. Bell does not mention whether or not the 

 bud was provided with an anus. If it had no anus, the two 

 buds are not comparable. Clapar^de was of opinion that the 

 budding in a Serpula examined by him might have been 

 caused by a lesion, and M'lntosli, in reference to SijUis 

 raviosa, considered tliat budding may take place at any point 

 in consequence of lesion at that point. If it is taken for 

 granted that at one time this eartiiworm existed in a normal 

 condition, viz. that the anterior trunk and the left appendage 

 made up the normal Lianbricus, and that the right appendage 

 was developed some time after, the origin of tiie riglit-liand 

 appendage might be explained thus : — Assuming that seg- 

 ment 54 had in some manner been cut or pierced (the wound 

 extending into tlie interior of the intestine), some of the 

 earth passing through the intestine during the process of 

 alimentation may have been diverted through this opening 



