Regeneratioti iii Lufiihnnilus 571 



the heteromorphic tail from the old one, exactly at the line of their 

 union. Unfortunately, both pieces soon died after the operation. 



E Sonii' Conuueiits 011 Anterior Re^etieration 



Although this subject was pretty thoroughly studied by Biilow 

 and V. Wagner, there are some points that have not been considered 

 at all. 



In the formation of the new head, abnormalities are not infre- 

 quent. Double heads, arising immediately from the cut surface; 

 or from a common stalk a little distance from the cut surface occur 

 in about 5 to 10 per cent of the pieces. At the posterior cut sur- 

 face, on the contrary, double malformations are of very great 

 rareness. The only instance I find recorded in the literature is 

 that spoken of by Biilow, of a worm developing a double tail, and 

 another similar instance which I found last summer. From the 

 posterior cut surface there grew out two tails of somewhat differ- 

 ent lengths, and the whole worm had a Y-shaped form. 



By observing the process of regeneration of an abnormal head 

 one will be impressed by the constant movements that are going on 

 inside the body-walls in a forward direction. These exert a great 

 pressure upon the delicate regenerated epidermis, causing it to 

 protrude in many points. This action may be largely responsible 

 for these malformations, for if, on the other hand, the malforma- 

 tions are supposed to be due to the operation, why should we not 

 find abnormalities in the regenerating tail also ? I have never 

 observed any malformation of the head of Lumbriculi freshly 

 caught in ponds. Another point that I wish to call attention to 

 is the dissimilarity between a regenerated and a normal head. 

 "Das Vorderende ist immer etwas grimlich oder griinschwarz, 

 was von dem Pigmente herri.ihrt, welches namentlich die den Darm- 

 kanal bedeckenden Dri'isen erfiillt."*^ This green pigment is 

 arranged segmentally m seven to eight very deeply colored bands, 

 which give to the head a striped appearance. If from one to seven 

 of the anterior segments are removed, the number removed will be 

 restored, but the substituted segments lack the pigment, and are 



' Fr. Vejdovsky. 



