355 



kind were observed) proves that the single abnormality cannot be attri- 

 buted to the artificial fertilisation; in other words, the cause of the 

 abnormality, whatever it may have been, was the same as that which 

 produced the similar abnormalities found in frogs living under natural 

 conditions (see literature quoted). 



During the tadpole stage the two additional legs were placed one 

 on each side of the noruial appendage belonging to the left side of the 

 larva, although they both arose from one spot situated a little above 

 and behind the origin of the normal limb. One of the additional legs 

 [A) protruded under and in front of the normal limb, and when elong- 

 ated it also turned dorsally with the plantar surface of the foot upper- 



Fiff. 1. 



Fio-, 2. 



Figs. 1 and 2. ^4, the left additional limb; B, the right additional limb; C, the stalk 

 bearing the two additional limbs in the young fi'og; D, plate representing the aborted 

 fused thighs of the additional pair of legs. C and D are represented on a larger scale 



in the right hand sketch. 



most. The other additional leg [B) extended posteriorly and when 

 elongated lay under the tail just to the left of the median line, also 

 with the plantar surface of the foot uppermost. Both of these additional 

 legs retained until a short time before the metamorphosis some slight 

 power of movement, and were directly connected with the body but 

 before metamorphosis had set in they had become quite useless and 

 were clearly attached to the body by a stalk only. During the meta- 

 morphosis too the legs had changed their position, both being posterior 

 to the normal limbs. 



The condition of things in the young frog is shown in fig. 2. From 

 this it will be seen that the thin stalk (C) arises dorsally on the left 



24* 



