92 W. N. F. WOODLAND 
reproduced tail is only reproduced for the purpose of being 
shed, and in consequence the regenerated tail is grown on 
cheap ‘ jerry-built ’ lines sufficient for the end in view. That 
this is the explanation will be clear, on the one hand, when we 
call to mind the regenerated tails and limbs of Urodeles, arms 
of Starfishes and Ophiuroids, and limbs of Crabs, Centipedes, 
and Plasmids (walking-stick insects), all of which, when 
regenerated, are required for use as integral parts of 
the organism and are therefore of normal type *; on the 
other hand, the fact that the organism can actively mould 
an autotomous appendage so as to adapt it for functions not 
connected with its own individuality is shown in such cases 
as those of the hectocotylized arm of Dibranchiate Cephalopods 
and the heteronereis segments of Polychaetes. According to 
this explanation then, the aberrant scaling of the regenerated 
Gecko tail is to be regarded as that form of scaling most easy 
to be produced under the circumstances, just as the simple 
longitudinal muscles (devoid of connexion with the endo- 
skeleton) and regenerated nerve cord (devoid of white matter, 
cancion cells, and nerves) are to be regarded as similar products 
of a ‘ jerry-building ’ policy, and not due to a mere reversion- 
‘to-type tendency, as supposed by Boulenger.” The type of 
sealing of the regenerated tail may happen to be of an ancestral 
type simply because this latter chances to be a ‘ cheaper’ or 
‘to-hand ° form of lepidosis, but it is quite evident that since 
the ‘reversion to an ancestral type’ explanation does not 
apply to the internal structure of the regenerated tail, it also 
cannot be held to be sufficient to account for the scaling. 
I may mention that previous to preserving the tail (of 45 days’ 
srowth) of one of these five Geckos, I held it with my fingers 
1 The well-known examples of an antenna being generated on the eye- 
stalk of Palinurus, of a mandible being substituted for a first antenna in 
Asellus, and a wing replacing the hind leg of the moth Zygaena (vide 
Bateson, ‘ Material for the Study of Variation’, 1894), and other similar 
examples are of the same category, the ‘controlling’ influence of the 
organism as a whole, however, being at fault, the reproduced part being 
out of position. 
* Boulenger, G. A., ‘ Proc. Zool. Soc.’, Lond., 1888, p. 351, 
