1133 
Now in the present investigation it has been proved that manganese 
ions (Mn°°) also act as a positive catalyst in the oxidation of tartaric 
acid, lactic acid, malonic acid ete. 
Thus light and manganese ions (Mn°) play the same role in these 
oxidations with KMnQ,,. 
Since numerous chemical actions have been shown to be markedly 
accelerated by light, hence light may be regarded as a positive 
catalyst of great generality. 
Presideney College Calcutta. Imperial College of Science, London. 
Physiology. — “On the structure and covering of the trunk- 
dermatomes of the cat’. By Dr. S. pr Borr. (Communicated 
by Prof. G. van RIJNBERK). 
(Communicated in the meeting of December 18, 1915). 
The investigations of EckKnarDp have already proved that two 
adjoining dermatomes partly cover each other. The measure, in 
which this covering takes place, could up to the present moment 
only be ascertained by calculation. [t was not yet possible to do so 
experimentally, because with one and the same animal two adjoining 
dermatomes had never yet been determined by physiological methods 
of investigation. The method of isolation, hitherto most followed, 
by which towards the head and the tail of one hind root two 
were cut, excluded, as a matter of course, the possibility of deter- 
mining two adjoining dermatomes. In 1911 however DussEr DE BARENNE 
invented a new method for the determination of dermatomes. This 
method is founded on the fact that with local poisoning of the spinal 
cord on the spot where one hind-root enters, the dermatome belonging 
to it, shows a syndrome consisting of three sorts of phenomena, to 
which belongs a.o. also hyperreflexion. Dusser pe BARENNE moistened 
the spot where it enters with a piece of cotton wool drenched in a 
coloured solution of strychnine (1°/,) that had previously been 
squeezed out. He could then easily limit the hyperreflectory field 
of skin. According to this method Barenne determined a.o. the 
dermatomes of the hind leg with the dog, and found in this way 
fields of skin, corresponding with the dermatomes in the same kind 
of animal, determined by Winker and van Risxperk according to 
the isolation method. KrrsseNs determined the dermatomes with cats 
chiefly according to the strychnine-isolation-method. He applied the 
strychnine-method of Dusser DE BARENNB combined with the isolation- 
method. On both sides of the moistened root he cut one or two 
roots. In this way he determined in a cat the root-field of thoracalis 
