Zoology. — “Rhythmical Skin-growth and Skin-design in Amphibians 
and Reptiles’. By Prof. C. Pa. Siurrer. 
(Communicated at the meeting of March 27, 1920). 
VALENTIN HARCKER') in a few very important communications and 
later on in a synthetic exposition has tried to give due value to a 
factor, until now little or not at all appreciated, in the explanation 
of the origin of the skin-design. Previous investigators, among whom 
I refer to Harrison, ALLEN, ToRNIER, Grosser, ZENNECK and especially 
to v. RinBerkK, chiefly tried to find a connection between the trans- 
versal stripes of the vertebrata and the segmental arrangement of 
other organs. ZENNECK, among others, found a connection between 
the appearance of pigment in the skin and the situation of blood- 
vessels in embryos of Tropidonotus natrix. The well-known researches 
of v. Rrunperk, partly made in collaboration with Winkrer, to which 
in some respects the work of others (SHERRINGTON, BOLK, LANGELAAN, 
etc.) is connected, try to find the most important factor for the 
origin of the skin-design in the segmental innervation of the skin. 
Thus the — in my opinion — ill-chosen term of ‘‘dermatome” 
has found its way into the scientific terminology. This term gives the 
impression as if the skin itself had a metameric structure, while the 
expressions of “overlapping of the dermatomes”, “summation and 
interferential zones of the dermatomes”’ all reinforce this erroneous view. 
Though some of the investigators have made it plausible, that in 
a number of cases the innervation and the design of the skin are 
correlated, yet one cannot derive from it a general guiding principle 
in explaining the design of the skin, and I think that we find in 
Haxcker’s principle a wider base on which one might build with 
profit. This principle is described by Hacker as follows: the skin-design 
of the vertebrata (and I prefer to add: also of the invertebrata) is 
dependent on the fact that the growth and the differentiation of the 
skin are clearly rhythmical. This rhythm is sometimes in correlation 
1) V. Harncker. Entwickelungsgeschichtliche Wigenschafts- oder Rassenanalyse 
Z.f. ind. Abstammungs- und Vererbungslehre. Vol. 14, p. 260, 1915. 
Idem. Zur Eigenschaftsanalyse der Wirbeltierzeichnung. Biolog. Centralblatt 
Vol. 36, p. 448, 1916. 
Idem. Entwickelungsgeschichtliche Eigenschaftsanalyse. Jena 1918. 
