i the right. 
( 208 ) 
Figure 4. Mesial wall of the left hemisphere. 
Figure 5. Mesial wall of the right hemisphere. 
c-m = fiss. calloso-marginalis. Broken neither on the left side nor on 
r — fiss. ro8tralis. 
rh = fiss. rhimlisposterior. 
p o = fiss. parieto-occipitalis. On the left side a broad gyrus cuneo-praecunealis 
is observed, which on the right side is only indicated as the beginning 
of a deep pli de passage about on the middle of p o. 
ca = fiss. calcarina, confluent with p-o. 
cc — corp. callosum. 
Not indicated are: foramen Monroi ; immediately in front of this: 
commissura anterior. On the base the optic chiasma and the mammilary 
bodies. On the left side behind the thalamus the pulvinar. 
Figure 6. Ventral wall of the left hemisphere 
Figure 7. Ventral wall of the right hemisphere. 
co = fiss. collateralis (= occipitotemporalis). 
h = fiss. temporalis inferior, which extends in anterior direction in front of 
the posterior part of the large fiss. rhinal, posterior (apes!). 
/s = fiss. frontalis inferior (incisure and H. [Broca]). 
Mathematics. — “Investigation of the functions which can be built up 
by means of infinitesimal iteration. Contribution to the solution 
of the Junctional equation of Abel.” By M. J. van Uvkn. 
(Communicated by Prof. W. Kapteyn). 
If we regard by the side of also y,(4 
y»==yf^*)|=y[y{</(®)!]=etc_ y H =<p n (*) .. ., we can ask 
ourselves whether this “iteration” of the function qlfi) leads to a 
definite final value y v , when it is continued to infinity and how this 
final form behaves from the point of view of the theory of functions. 
In this sense the problem of iteration has been taken by numbers 
of mathematicians, among others by E. Schroeder *), Koenigs*), 
FARKAS *), ISENKRAHE *), BoURLET s ), L^MERAY 6 ), CARLSSON 7 ). Their 
considerations lead more than once to the construction of new algorithms 
to approximate roots of algebraical and transcendental equations. 
Others on the other hand have put the question: which function 
x ) Math. Ann. Bd. II (1870), p. 817. 
2 ) Bulletin des sc. math. t. VII (1883), p. 340; Ann. scientif. de l’Ecole norm, 
sup. (3) t. I (1884), suppl. p. 3; t. II (1885), p. 385. 
s ) Journal de mathem. (3) t. X (1884), p. 101. 
4 ) Math. Ann. Bd. XXXI (1888), p. 309. Das Verfahren der Funktionswieder* 
holung, Teubner, 1897. 
B ) Ann. d. 1. Fac. des sc. de Toulouse t. XII (1898), G. 
6 ) Among others Bulletin d. 1. Soc. Math. t. XXVI (1898), p. 10. 
T ) Om itererade funktioner. Diss. Uppsala, 1907. 
