960 
point a white stripe appears. In this way a few more stripes occur 
on the convex side of the embryo, than on the concave side (Fig. 6). 
Fig. 5. 
I saw the same phenomenon take place wherever the trans- 
versal striated parts of an embryo lay in a sharp curve. This 
was very obvious in the tail of the embryos of 
Gecko verticillatus, the well-known Tokkè of the 
Dutch Indian Archipelago. The embryo’s tail is 
curled like a spiral, turned a little dorsally. And 
here too we find that considerably more cross- 
stripes appear at the ventral convex side than 
at the concave dorsal side. (Fig. 7). The same 
phenomena appear on the tail and the trunk of 
crocodile embryos, as is generally known. 
The question is raised now: what is the origin 
of this phenomenon? | think that we must look 
for the explanation in the rhytmical skin-growth. 
At the convex side the growth is certainly more 
energetic than at the concave side, where the 
body is compressed and the skin is not so tightly 
stretched and has even a few folds. For the 
present it may be left an open question whether 
the reason is an insufficient nourishment at the 
concave side, caused by pressure on the blood- 
vessels and probably on the nerves, as Gusr. 
TORNIER ') supposes has taken place in an analogous 
case of snake embryos, deformed pathologically. 
1) G. TornipR, Le. p. 1210. 
