HETEROMOEPHOSIS 119 



repeated and confirmed. I am not in a position to state 

 whether they are correct or not. 



The theory given by Bonnet is in some points similar to 

 a theory brought forward by Duhamel in his Physique des 

 arbres, and to which Sachs goes back in his papers on 

 "Stoff und Form der Pflanzenorgane." 1 



Bonnet believes that just as there are specific germs for 

 the development of the entire animal, there are also special 

 germs for the development of the various organs ; he assumes 

 the existence of certain head germs and certain tail germs. 

 In order, however, that these germs may develop, they must 

 be particularly well nourished. Their nutrition is accom- 

 plished, as in plants (according to Duhamel), by various 

 kinds of saps, one of which serves for the nutrition of the 

 head, while the other nourishes the tail. The latter flows 

 from head to tail, the former in the reverse direction. If, 

 now, the head is cut off, the saps which heretofore served to 

 nourish the head, can now be utilized for the nutrition of 

 the head germs, and the latter begin to grow out at the cut 

 oral end into a new head. In a similar way the tail germs 

 may begin to grow when the tail is cut off. It is assumed 

 that the tail germs and the head germs are distributed 

 evenly throughout the body of the vers rougedtres; for this 

 reason a head must always grow from the oral end of a 

 fragment cut from any portion of the animal, while the 

 aboral end must always give rise to a tail. Upon the other 

 hand, in the vers blanchdtrcs the head germs are found 

 only in the neighborhood of the head, while the tail germs 

 are distributed through the entire body. For this reason 

 the worm regenerates a new head when the head is cut off, 

 while a new tail is formed at either end when a piece is cut 

 out of the middle of the worm. 2 



l Arbeiten des botanischen Institute in Wttrzburg, herausgegeben von SACHS, 

 Vol. II (1882), pp. 432 and 689. 



2Cn. BONNET, Consideration eur les corps organists, Art. 259 ff.; (Euvres (Neu- 

 chatel, 1779;, Vol. VI, pp. 48 ff. 



