955 
with the metamerism of the body, but generally independent of it 
and in a high degree autonomic. 
It is evident that it is easiest to trace the phenomena of this 
rhythmical growth in young animals and especially in quickly growing 
larvae or embryos. Thus HarckKer found this rhythmical growth for 
the first time confirmed in the larvae of Axolotl, as here the size 
of the cells, of which the epidermis is constructed and the fact that 
it has only two layers of cells, was very favourable for the research. 
The large number of embryos and larvae of reptiles and of 
amphibians of which the Zoological Laboratory at Amsterdam disposes, 
led me to investigate the rhythmical growth in the skin of these young 
animals with a view to afford a further confirmation of HAECKER’s supposi- 
tion, that this rhytmical growth is the nearest cause of the skin-design. 
As to the larvae of the amphibians, I examined the skin of the 
of Megalobatrachus mazimus-larvae of the famous hatch of the 
Aquarium of the Society “Natura Artis Magistra’’. These larvae show 
very early a skin pigmentation, but I never found a metameric design, 
as Harcker did in Axolotl. The pigmentation of the Megalobatrachus- 
larvae might rather be called diffuse, but not absolutely, as it is obvious 
on closer examination that the pigment, especially on the ventral 
side, is arranged more or less regularly in small groups. 
The idea struck me directly, whether this were a case of a type 
of skin-growth which was indicated by Haxcker as the ““chess-board- 
type’, — theoretically possible, but not yet observed — and which 
was accepted by him as the possible original type of the skin-growth 
of the vertebrata. , 
1 found on microscopical examination of the skin of the larvae 
of Megalobatrachus maainus, but especially in. a young stage of 
30 m.m. length, where the pigment formation was only in its first 
development, that the epidermic-cells were arranged very regularly 
indeed, into square fields in which, evidently. the growth had proceeded 
centrifugally (Fig. 1). The cells lying in the middle of every field 
were separated inore sharply by more strongly developed marginal zones 
than the younger ones lying against the edge. The very first pigment 
granules appear in the middle of these square fields. This agrees 
with the observations, made by Gustav TorNier *), who found that 
no pigment appears in cells that are still in the dividing stage, but 
as a rule in those parts of the skin which are growing rapidly. 
These spots, arranged regularly on the ventral side of the larvae 
') G Tounten. Experimentelles über Erythrose. Sitz.ber. Ges. Naturf. lreunde. 
Berlin 1907. 
