306 ENTOZOA. 



granular matter. I cannot call the inner tube a true nervous cord, 

 but, at the same time, I am willing to believe tbat it represents a 

 rudimentary condition of a true nerve-system. Bbertli regards tbe 

 lateral lines as vascular, but Schneider and others are very positive 

 as to the existence of an internal central as well as an external peri- 

 pheral nerve-system in these worms. According to Schneider, an 

 abstract of whose views on this point are given by Mr. Busk in the 

 "Microscopical Journal" for 1863, the nervous system in ^scan's 

 megalocephala may be described as follows : — " The nerve-collar is 

 placed about one line below the oral orifice. From it six cords are 

 given off in front ; four of these (nervi submediani) arise nearly in 

 the middle, between the border of one of the lateral intermuscular 

 spaces and the middle line, though rather nearer the lateral space. 

 The roots commence with a broad base, which gradually narrows 

 into the slender cord. Two other nerves {n. laterales) he in the 

 centre of the lateral intermuscular spaces. These nerves are 

 completely imbedded in the substance of the lateral space, and they 

 may, with some pains and trouble, be at once dissected out, or may 

 be seen more readily, but still distinctly, in simple transverse sec- 

 tions. Two strong nervous cords pass backwards ; they arise on 

 the ventral surface of the ring, one on either side of the ventral 

 Hne, towards which they tend in a sort of arch, and are continued 

 a short distance, but they cannot be traced beyond the arched 

 anastomosis of the water- vascular system, which lies a short dis- 

 tance behind the nerve-collar. These are termed rami communi- 

 cantes." Schneider then proceeds to describe numerous ganglion 

 cells in connection with these various true nerve-structures, but 

 it is needless to speak minutely concerning them. If I understand 

 his descriptions rightly, the ordinary lateral vessels are referable, 

 as Eberth and many others stiU suppose, to the water system, 

 whilst the nervous cords are altogether independent. 



I pass on now to the consideration of the reproductive system. 

 As regards the male, the testis consists of a single, slender, and 

 extremely delicate spermatic tube, which is frequently coiled upon 



