24 
normal substances, so that neither the mercury halides, nor those 
of Sb exhibit any association. The molecular formulae for these 
latter compounds will, therefore, no doubt be SbCI, ete., and not 
Sb,Cl, ete. 
After these somewhat lengthy expositions [ can be a good deal 
shorter in future, now that the Methods for the further calculation 
have been sufficiently set forth and elucidated by the examples of 
mercury and also of antimonium. 
In the determination of the values of 6; and pa, for the diffe- 
rent metals and the remaining elements of the periodic system we 
shall, therefore, have to refer continually to this second Paper. 
Aluminium, Borium, Arsenicum, Bismuth, Tellurium, Silicium etc. 
will be treated first. 
Clarens, March 1916. 
Zoology. — “On the Setal Pattern of Caterpillars.” By A. Scmmr- 
BEEK. (Communicated by Prof. J. F. vaN BEMMELEN.) 
(Communicated in the meeting of March 25, 1916). 
In 1876 Weismann proved the ontogeny of the peculiar colour- 
patterns occurring in many Sphingide-caterpillars to be a further 
differentiation of the linear ornamentation. From this he concluded 
that the ocellar and annular markings had also phylogenetically 
taken origin from longitudinal stripes, and he could back this in- 
ference by the fact, that the intermediate stages, which in some 
genera and species were passed through during their growth, 
acted as terminal stages in other forms. From that time onwards 
many investigators have occupied themselves with the study of the 
„external appearance of caterpillars. Independently of each other 
Wina. Mürrer and Dyar ealled attention to the regular arrangement 
of the setae in different families; O. HOFMANN, PACKARD, QUAIr, 
Tsou') and others followed them in their track. 
J. KF. vAN BEMMELEN (1913) pointed out the connections between 
the colour-pattern of caterpillars, pupae and imagines, which indeed 
had been remarked by other students, e.g. Pourron, but had not 
been considered of real importance. VAN BrMMELEN’s views therefore 
introduced a new aspect into the discussions,, as he defended the 
homology of pigmentspots with tubereula and setae. This connection 
1) Tsou’s paper only came into my hands, after the writing of the present 
communication. 
