1917] Chordotojial Organs of Cerambycid Larvce. 69 



STRUCTURE OF THE NERVE END ORGAN OR 

 SCOLOPOPHORE. 



In the two species, Ergates spiculatus Lee. and Monohammus 

 confusor Kirby, which were studied for their histological struc- 

 ture, there was found a pair of chordotonal ligaments in each 

 of the first eight abdominal segments. Since these organs were 

 alike structurally, a description of one will suffice for both 

 species. Sections were cut of these ligaments in the different 

 abdominal segments of these two species, and also of Mallodon 

 dasystomus Say, and it was found in every case, that each of 

 the eight pairs of cords contained four nerve end organs or 

 scolopophores. 



The scolopophores of the cerambycid larvas correspond in 

 general to those of other orders of insects, and are especially 

 similar to those described by Schwabe (1906). Each is a nerve 

 end organ, composed of a ganglion cell, and two enveloping 

 cells. The ganglion cell or, better, the sense cell, is elongated 

 and covered on its distal end by two enveloping cells, forming a 

 sack-like structure about the distal end of this cell. The distal 

 one of these two enveloping cells serves to unite the end organ 

 with the hypodermis, and is called the cap cell. (Figs. 7 and 8, 

 C. C). The other one of the two cells (E. C.) lies between the 

 cap cell and the enlarged portion of the sense cell, while 

 proximad to this cell is found the body of the sense cell (S. C), 

 with its continuation to the nerve (Ch. N.). 



The sense cell (Figs. 7, 8 and 9, S. C), which contains the 

 axis fiber (Fig. 9, A. F.), is of the bipolar nerve type, continuous 

 proximad with the chordotonal nerve (Ch. N.). Its distal por- 

 tion penetrates the center of the enveloping cell into the 

 proximal end of the cap cell, where the nerve enlarges to form 

 the peg-shaped body or scolopale (Sc). The cell enlarges in its 

 middle portion, in which region is found a large spherical 

 shaped nucleus, containing large and fine chromatin parts. The 

 cytoplasmic structure is similar to that of other nerve tissues. 

 An axis fiber runs nearly straight through the sense cell, except 

 where it bends around the large nucleus. As it enters the 

 proximal end of the cell, it is very small, but as it approaches 

 the distal end, it gradually becomes much enlarged. However, 

 at the point where it enters the peg-shaped body, or scolopale, 



