THE TRACHEAL SUPPLY IN THE CENTRAL NERVOUS 

 SYSTEM OF THE LARVA OF CORYDALIS CORNUTA L. 



William A. Hilton, Cornell University. 



This study was begun with two main objects in view. First, 

 to determine some land-marks for use in a study of the finer 

 structure of the gangHa and nerve cells of this insect; and second, 

 to determine the exact air supply of each ganglion for the pur- 

 poses of later experimentation. 



It is well known that all of the organs of insects are abun- 

 dantly supplied with tracheae and many fine tracheoles, but the 

 number and dense arrangement of the minute tracheoles in many 

 of the organs comes as a surprise to the person who sees them 

 under a microscope for the first time. The central nervous sys- 

 tem is no exception to other organs, indeed the tracheoles are 

 very abundant in all parts of the nervous system. 



One of the disputed points in regard to the tracheae is the ques- 

 tion whether the minute tracheoles anastomose with each other 

 or not. They are very abundant, they branch to some degree 

 and they are very long and wind and twist themselves into such 

 a dense mat that it is very hard to follow individuals and hard 

 to tell whether they unite or not. 



There seems to be very little literature on the tracheal system 

 of Corydalis. N. Young Burke, in an unpublished thesis in the 

 library of the Department of Entomology of Cornell University, 

 shows the main tracheae of the tracheal system of Corydalis. In 

 her figures, ventral transverse tracheal branches running from 

 side to side are shown. It is from these ventral transverse branch- 

 es that most of the ganglia are supplied. 



The subesophageal ganglion has two branches which come 

 from the trans\'erse ventral cephalic trachea and run to the ceph- 

 alic part of the ganglion on either side. This ganglion is also 

 supplied by two other branches, one on either side in its caudal 

 region. These come from another source more caudad of the 

 ganglion. 



The three thoracic ganglia all receive two branches, one on 

 each side from a ventral transverse trachea, which like the 

 tracheal branch of the upper part of the subesophageal ganglion 

 come to the ganglia from a cephalic direction. 



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