THE YOUNG SCIENTIST. 
69 
cupied with other business, and pays no 
attention to their proceedings.* The 
ordinary movements of insects appear to 
be of this character, and to be excited by 
the ganglia belonging to the segment to 
which the moving limbs are attached. 
Thus a centipede will run, after its head 
has been cut off, and a water-beetle {Dy- 
tiscus) swam energetically when thrown 
into water after its brain has been re- 
moved. t 
It must not, however, be assumed that 
the brain of insects has nothing to do 
with their movements. It is i:>robably 
the means of co-ordinating or directing 
them to a common end, and gives rise to 
what are called consensual movements, 
that is, movements which are accompa- 
nied or stimulated by a sensation, al- 
though not controlled by a will. In man 
these actions are frequently exhibited, 
" as when laughter is provoked by some 
ludicrous sight or sound, or by the re- 
membrance of such at an unseasona,l)le 
hour. "I Sneezing is another instance of 
a sensation leading to certain motions, 
without any intervention of the human 
will. 
Speaking of these consensual motions. 
Dr. Carpenter observes, " It is probable, 
from the strong manifestations of emo- 
tion, exhibited by many of the lower ani- 
mals, that some of the actions which we 
assemble under the general designation 
of instinctive are to be referred to this 
group." 
The insect brain is composed of a supra- 
oesophagal ganglion and infra-oeso]^hagal 
one. Von Siebold says, the first corres- 
ponds to the cerebrum of the vertebrata, 
and " the second is comparable, perhaps, 
to the cerebellum or spinal cord."§ The 
superior ganglion gives off nerves to the 
antennae and eyes, the lower one to the 
mandibles, etc. So far as is known the 
insects that exhibit the most intelligence 
have the largest and best developed 
brains. 
A special volume w^ould be required for 
anything like a complete examination of 
the little which is known on this subject, 
but these few remarks may assist the 
microscopic beginner in examining the 
movements of his subjects, and guard 
against the error of referring to reason 
and volition those which are probably, 
either the direct result of stimulants ap- 
])lied to the surface fas in nerveless crea- 
tures), or the indirect (reflex) result of 
such stimulants in beings like the rotifers, 
wdio have a nervous system ; or the result 
of sensations, which excite actions with- 
out previously referring the matter to the 
*See Carpenter's " Manual of Physiolog'y." 
t Carpenter's " Manual of Physiology," p. 551, 
t Ibidi, p. 543. 
§ " Anatomy of Invertebrates," Burnett's tranp. 
decision of a will. It must not, however, 
be too readily assumed that the beha- 
vior of creatures possessing distinct or- 
gans is entirely automatic ; and we must 
not forget that even the best physiologists 
know very little concerning the range of 
functions which the nervous ganglia of 
the invertebrata are able to discharge. 
Astronomy for Amateurs. 
BY BEEIiESr H. WRIGHT. 
(All calculations are for the Latitude and Merid- 
ian of New York City.) 
THE PLANETS FOE MAY, 1882. 
Meecuey may be seen during the last few 
days of May and the first of June as an evening 
star settmg as follows : 
May 26, 9h. 12m., evening. 
" 30,9 14 
June 3, 9 13 
He may be seen about 5° north of the sunset 
point. Venus and Mei'cury approach very 
closely on the 29th and 30tli. Venus being dis- 
ting'uisliai)le by her suj^erior apparent diameter, 
milder light and by being south of Mercury ; 
separated, however, by less than 2°. This will 
be an interesting occurrence to witness, which 
none should fail to see. 
Venus is rapidly receding from the Sun and 
moving eastward past the fixed stars. At the 
beginning of the month she is in the eastern 
part of Aries and between the Pleiades and 
Hyades, and on the 5th she passes Jupiter, be- 
ins' wdien nearest, about one degree north of 
him. Then passing over several degrees she 
enters the milky way. About the 20 th and on the 
29th she passes Mercury and proceeds eastward 
into Gemini. She will be about 15° S.W. of 
Castor and Pollux on the 30th. 
She sets as folloAvs : 
May 10, 8h. 39m., even. 
" 20,9 1 
" 30, 9 19 
Maes is about 20° east of Venus and in the 
Constellation Can(^er. He is in the group 
Propsepe on the 18th, and (f north of the Moon 
on the 22d. He sets as follows : 
May 10th, Oh. 26m., morning. 
" 20 11 59 evening. 
" 30 11 36 
JupiTEE is too near the Sun to be successfully 
observed, being in conjunction with the Sun on 
the 30th. 
Satuen, too, is invisible, being in conjunction 
with the Sun on the 6th, as is also Neptune. 
total ECLIPSE OF THE SUN. 
The Sun will be totally eclipsed on the 17th. 
This eclipse is visible throughout all of the 
