[74] REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
ganglia themselves by cutting tliein apart in a longitudinal as well as transverse di- 
rection. These lesions produced phenomena which were quite varied, and which suc- 
ceeded, from moment to moment, in an order more or less determinate. A longitudi- 
nal section, dividing u rually the suluesophagcal ganglion, gave rise to some lateral 
movements; the insect turned as if rearing up like a horse mundijn), at tirst mo- 
nientarily from ;!ie side of the wound, then definitely from the opposite side ; it fell 
over on its back from the side opposite the wound, and, in rising, made a complete 
revolution. It lost the power of leaping. The transverse section of the same ganglion 
produced some accidents much more grave. The cricket raised the right foot, as if to 
find a point of support, and tumbled over often to the left; while on the other side 
we could not succeed in reversing it. The reflex act ions were sufficiently pronounced. 
The section of a single cord of the chain does not produce cross effects. It intro- 
duces a dist urbance in I hi' equilibrium of the fund ions of relat ion of the two sides oi 
the body, and is always indicated by the insect's walking in a circle, the feet on on< 
side functioning more rapidl.v than those on the other, &e. 
In combining the different seciions which precede, or in cutting simultaneously the 
two cords on a point of their tract, and a single one between them on some other 
point, we obtain some complementary information as to the mode of transmission oi 
nervous actions. 
The result of these experiments establishes the fact that the transmission of the will 
is always made directly, and without a transverse effect, while the reflex actions, 
although they are transmitted more easily by a direct course, take, place, though 
with less intensity, by a transverse effect. Another general fact that Yersin has in- 
ferred from his experiments is that the maximum of intensity of the movements which 
he has observed after the operation has always occurred on the side, on which the opera- 
tion was made. This is why in its rearing gait (marche en manage) the insect turns in 
a circle from the opposite side. So when we make the section of the right cord be- 
tween the head and thorax, the animal begins at first to turn to the right, but at the 
end of a moment it changes and turns to the left. It is, indeed, immediately after the 
section of the right cord that the right feet cease to be submitted to the action of the 
will, while t hose of the left side continue to obey the will, acting with more activity, 
and thuscausing the insect to turn to the right. lint at the end of an instant, the re- 
flex action setting in motion the right feet, this impresses upon them a more lively 
movement than to the left feet, which act under the direct impulse of the will, and 
they consequently turn the; insect to the left. For the same reason, the insect 
placed on its back will recover itself on the wounded side. 
As the result of later experiments, read before the Soci6t<5 Helvc'tique des Sciences 
Naturelles, at Lausanne, in 1831, Yersin stated that each ganglion can become the 
poinl of departure of spontaneous movements and a center of distinct perceptions. 
The following is an abstract of his memoir to the French Academy, the observations 
having been made in 1856, aud relating to the effects of the section of the cords or 
commissures connecting the ganglions of the nervous cord: 
1. The co-ordination of movements is not disturbed by the section of two cords at a 
time at any point whatsoever of the chain. 
2. On the contrary, locomotion becomes abnormal, (1) every time we cut a single 
cord at a point from the anterior chain to the ganglion of the metathorax ; (2) every 
time we make two or several sections, each on a single cord, between different gan- 
glia, one at least of the sections being situated on a point anterior to the metathorax. 
3. In the vertebrate animals the nerves properly so called have all their roots in 
the elongated medulla and in the spinal marrow. In the articulates almost all the 
nerves arise from the ganglia. Anatomical analogy leads us to compare the ganglia 
of the chain to a marrow. 
4. The experiments here given in resumd 6eem to us to establish the fact that it is 
the ensemble of the cephalic and thoracic ganglia which preside over the co-ordination 
of locomotive movements without its being possible to ascertain whether this function 
resides in one of these organs to the exclusion of the others. Thns this marrow rep- 
resents at the same time the cerebellum of the higher animals. 
5. It is very probable that it is therefore in the reunion of the ganglia that wo 
should seek the analogy of the brain of vertebrates. 
