Figure 16 shows us the complete junction of all the connective filaments traversing the ganglion; first the ventral column, with the connective ventral filaments starting from both its extremities; and then the three dorsal connective filaments, which preserve their individuality distinct, while they cross the dorsal lobe of the ganglion. The lower dorsal connective filament is distinguished from the others by a small compact mass of fibrillar substance through which it passes. We must note that the fibrillar substance becomes thicker at the point where the whole series of connective filaments enter the ganglion, and the same thing is repeated at the place where they leave the first thoracic ganglion to enter into the second. The ventral column is distinguished from the other parts of the ganglion by the dark color which it assumes through the action of the osmic acid; it presents black granules which, examined with a strong lens, show small fasciculi of fibres running in a parallel direction. The cells which line the lower surface of the ventral column do not throw out any prolongations; they are exceedingly small, but do not otherwise present any special feature. Figure 17 is but very slightly different from the preceding one: the ventral column is simply strengthened on its lower surface by the lower ventral lobule. The position of this lobule is interesting to note. We have already mentioned that each ganglion is divided into two halves by a column of conjunctival tissue, one anterior and the other posterior. In Section 17 we see the granulated projection of the ventral portion of this conjunctival column. In order to simplify it we have shown no conjunctival tissue in our illustration. We may nevertheless notice, that the nerve-cells at the point marked _c. c._ seem to separate one from the other, and show a triangular space between them, filled with conjunctival cells. If the segment had not been cut so obliquely, (and this obliqueness in the sections is almost unavoidable when dealing with such very small organs,) we should also perceive on the dorsal line of the section the projection of the dorsal part of the conjunctival column; in fact we shall see this projection in the figure which follows. The presence of the conjunctival column separates, as we have said, each ganglion into two parts, one anterior the other posterior. These portions are not at all symmetrical. We see in Section 17 that the lower ventral lobule is found only in the anterior part. Finally from the ventral column rises an important fasciculus of ascending fibres, which we have already seen in the horizontal diagrams; it is difficult for us to ascertain what these fibres are. In the 18th and last section we approach nearer the median line. The ventral column at this level has the appearance of being divided into two trunks. The ventral connective filaments are clearly seen upon its upper surface. Among the dorsal