ANATOMY. 



151. 



DUCTUS EJACULATORIUS. 



The DUCTUS EJACULATORIUS SEMiNis is that tube which extends 

 from the point of union of both sperm ducts or sperm bladders to the 

 commencement of the penis. It displays in its structure coarser 

 muscular fibres, and is of a more compact nature than the sperm duct. 

 It is analogous to the egg canal of the female organs, and appears 

 sometimes, like this, vesicular (Hydropkilus), and sometimes contracted 

 by degrees, consequently clavate (Lucanus, Lylta'), sometimes simple 

 and of equal width. In length it varies much, sometimes short, 

 scarcely visible, yet broad (Locusta, Gryllotalpa), sometimes longer, 

 but yet, in proportion to the other internal sexual organs, still short 

 (Calosoma, Melolontha, Trie/tins); moderately long when it attains 

 about the same length as the sperm ducts (Hydrophihts, Lytta, Meloe, 

 Papilio) ; long, lastly, when it is longer, indeed considerably so than 

 the sperm ducts (Lucanus, Lamia). The most remarkable form of the 

 ductus ejaculatorius I observed in Lamia cedilis. In this it is about 

 eight times as long as each sperm duct, and geniculated. But to display 

 this remarkable structure most justly, I must extend my description to 

 that of the entire sexual apparatus. 



If a male Lamia cedilis be opened from its back, we first observe in 

 the centre the convoluted intestine, and contiguous to it, on each side, 

 about the centre of the lateral space, two white testes. Both unite into a 

 narrow sperm canal, which runs towards the anus, and there unites itself 

 with the opposite one of the other side, after each has received a furcated 

 gluten gland. After a short course in a direct line, the ductus ejacula- 

 torius bends forward, runs in a serpentine direction up the central line 

 as far as the abdominal nervous cord, but beneath the intestinal canal, 

 as far as the thorax, and here again bends a second time, turning upon 

 itself like a knot, it then runs back again in a gentle curve to the anus, 

 there to pass into the penis. From its first bend, this duct is no longer 

 free, but it is enclosed in a wider membranous tube, into which also pass 

 eight delicate tracheae, the fine ramifications of which spread upon the 

 duct, and accompany it as far as the second bend, after they having one 

 after the other previously dispersed themselves in fine branches. But 

 from its second bend, the ductus ejaculatorius is accompanied by a strong 

 horny ridge, which lies in the superior portion of the enclosing tube, 

 retaining it tensely distended, and which terminates only where it passes 



