Haswett—A Monograph of the Temnocephalee. ie 
The intestine of Zemnocephala may be described as a four-sided, dorsi-ventrally 
compressed sac—varying considerably in shape, like some of the other organs, with 
the state of extension or contraction of the body. In close contact with it dorsally, 
at the sides, and to a greater or less extent on the ventral surface, are the lobes of the 
vitelline glands. Behind it presents a deep concavity in which the receptaculum 
vitelli is situated. 
The entire organ is invested with a thin layer of muscular fibres—a feature 
apparently only presented among monogenetic Trematodes by Sphyranura, though it 
oceurs in many of the Rhabdoceeles. The nature of this investment is not recognised 
by Weber, who calls it ¢axzca propria; but it is unlikely that in this respect there is 
any difference between 7. Sempervr and the other species. Passing inwards from this 
there are, in all the species I have examined, with the exception of 7. /heringit and 
Craspedella Spencert, a number of transverse bands of muscular fibres, which at 
regular intervals constrict the lumen of the intestine (PI. xiv. figs. 1 and 2, and PI. xv. 
fiz. 1). These septa, as they may be called, are continued outwards at the sides also 
by irregular bands of fibres which are affixed to the basement-membrane of the 
integument. By means of these the cavity of the intestine is partly subdivided, so 
that it consists of a central space and a series of pouches or cceca, which, as they are 
continued completely round, may be described as annular.* 
The main substance of the wall of the intestine, which is very thick, is composed 
of a greatly elongated epithelium. The cells of this epithelium are so loaded with 
granules that it is often quite impossible to make out their outlines: they are very 
long and very narrow and closely packed; in many cases they seem completely 
coalescent ; near its base each has a nucleus; internally each ends in a rounded 
club-shaped extremity, on which I have never succeeded in determining the presence 
of cilia. 
The substance of these cells is of an exceedingly fluid character : in the interior 
is an open reticulum of fine fibres. Numerous rounded or polygonal spaces occur ; 
these contain a clear colourless fluid, and enclose in each case one, more rarely two, 
large, strongly-refracting granules, which appear yellowish by transmitted light, and 
sometimes have an appearance as if they were composed of concentric laminz ; these 
were observed to be undergoing brownian movements, showing that they lie quite 
free in the watery fluid of the vacuole ; active Bacteria were observed in the interior 
of one or two of these vacuoles in some cases. There can be little doubt that these 
granules, which are nost abundant near the inner surface of the epithelium, are of an 
*I do not understand Braun when he says with regard to my previous account of the septa that ‘‘die als Beweis 
dienende Abbildung eines Lingschnittes verdient einen solechen Glauben nicht, da offenbar nicht ein durch die Medianebene 
sondern seitlich davon gelangter Schnitt vorliegt” (/.c. p. 429). A median section was by no means necessary in order to 
prove the point. 
Q 
