HISTOLOGY OF THE LOCUST AND CRICKET. 
185 
of my own observations as I believe to be new. I shall give a more 
complete account of the digestive canal than of any other system. The 
figures on Plates II-VIII are numbered consecutively from 1 to 66. 
In order to make the relation of the various organs to one another 
more evident, and at the same time to explain the classification of the 
tissues, which has been generally adopted upon embryological grounds, 
I figure and describe two sections through the abdomen of the grass- 
hopper, Plate H, Figs. 1 and 2. They are both semi-diagrammatic, being 
intended to represent rather the general arrangement of the parts than 
their exact disposition in a particular section. To insure accuracy, 
however, the outlines of both the drawings were made with the camera 
lucida from actual sections, and these outlines were then changed only 
so much as was necessary to remove very slight irregularities. 
Fig. 1 is a transverse section through the abdomen of a female at the 
level of the posterior part of the stomach. The outer wall D, art, V, is 
shaded and represented of nearly uniform thickness, which is not quite 
exact. Outermost is the cuticula, next the epidermis, or cellular matrix, 
I and innermost the muscles — the three parts that make up the outer wall 
of the body. The same is true of the section through the male, Fig. 2. 
This section, however, is taken further back in the abdomen, being 
through the colon ; compare Fig. 45 col. The walls of the abdomen are 
divided into a large dorsal arch, D, and a smaller ventral arch, V, the 
two being united on either side by an articulating membrane, art, which 
will be described in speaking of the cuticula further on. The dorsal 
arch is really composed of the tergite and the pleurites fused together 
into one piece. 225 Within the body walls, which form, so to speak, a con- 
tinuous tube, there runs from mouth to anus a second tube of smaller 
diameter, the digestive canal, the general course of which is shown very 
clearly in a longitudinal section through a whole grasshopper, see Fig. 45. 
In a transverse section the digestive tract also appears (Fig. 1, St., 
stomach, Fig. 2, col., colon), separated by a considerable space from the 
body walls. In this intervening space there lie various other organs, 
notably those of reproduction. In the female, Fig. 1, it so happens that 
at the level of the stomach the sexual organs lie above the intestinal 
canal, while in the male, at the point represented in Fig. 2, the sexual 
organs lie partly above, partly below, the colon. In the female we notice 
first the round tubes of the ovary, Ov ; second, the ovarian ducts, ovd., 
and, third, on each side the large uterus, Ut, or upper end of the oviduct, 
into which the ovarian ducts open directly. In the male, on the other 
hand, we see the testes, Te., lying above the intestine, the single tubes 
round in section, being embedded in or surrounded by connective tissue 
(Leydig's zellig-blasiges Geivebe), and below the colon, col., lie the spermi- 
ducts or vasa deferentia, (v. def.) Finally, between the inner and outer 
tubes lie various muscles, the Malpighian vessels, and the numerous 
branches of the trachese. These are all left out in the drawing except a 
»» Oraber Die Tympaualen Sinnesapparate der Orthopteren. Denkschr. Wieti. Akad, Bd. 36 (1876), p. 76. 
