124 THE ANATOMY OF THE HONEY BEE. 



these things. Some authors have tried to prove that insects reason, 

 but the burden of joroof is still with them. We can admit that in- 

 sects iiiaij he possessed of very slight conscious intelligence, but we 

 can not admit that any one has ever proved it. Of course, a great 

 deal of very interesting insect literature owes its readableness to the 

 fact that the author endows his subjects with human emotions and 

 some intelligence, or makes it appear that they consciously do things 

 from a blind sense of obligation. The bee of literature is often quite 

 a different creature from the bee of science. 



If, then, we are forced to admit that we have no proof of intelli- 

 gence or of conscious sensations in insects, we have, on the other 

 hand, all the more evidence of a very high degree of nervous coordi- 

 nation. The body of a bee can be very greatly mutilated and the 

 creature will still remain " alive " as long as the nervous system is 

 left intact. The segments can be cut apart and each will yet be able 

 to move its appendages as long as its nerve center is not destroyed. 

 This shows that there are numerous vigorous centers of nervous 

 stimulation, but proper coordination results only when all the parts 

 are together and intact. 



The nervous system of insects (figs. 1 and 52) is comparatively 

 simple, consisting of a series of small nerve masses called ganglia 

 {Gng) lying along the mid- ventral line of the body, each two con- 

 secutive ganglia being connected by a pair of cords called the com- 

 missures." The ganglia contain the nerve cells, which are the source 

 of the stimuli sent out to the other tissues, while they also receive the 

 stimuli from the ectodermal sense organs. Thus there are incoming 

 or afferent stimuli and outgoing or efferent stimuli. The commis- 

 sures and the nerve-trunks that branch to all parts of the body con- 

 sist of fibers which are fine prolongations of the nerve cells. These 

 fibers are the electric wires that convey the stimuli to and from the 

 nerve centers and are of two kinds, afferent and efferent, according 

 to the direction of the stimulus each transports. 



In a generalized embryo we should theoretically find a nerve gan- 

 glion develoj)ed from the ventral wall of each segment, making seven 

 head ganglia, three thoracic, and at least ten abdominal ones. In 

 the adult, however, many of these fuse with one another. In the 

 head, for example, in place of seven ganglia there are only two, one 

 situated above the oesophagus, called the train, and one situated 

 below it and called the submsophageal ganglion. The connecting 

 cords are known as the circumoisophageal commissures. The 

 brain is composed of three embryonic ganglia, and in the adults 

 of many lower insects these are still evident as three well-marked 

 cerebral divisions or swellings, called the protocerebrum, the deuto- 

 cerehrum, and the tritocerehrum. The first carries the optic lohes 

 and innervates the compound and simple eyes, the second bears 



