74 THE ANATOMY OF AN AUSTRALIAN LAND PLANARIAN. 
homogeneous substance. The smaller ones are much less numerous than the larger 
and placed between them; both kinds originate in mother cells. In Geodesmus 
von Kennel found the rods much smaller and more of one form, spindle-shaped, with 
pointed ends. 
Jijima (7) denies the existence of two forms of rod-like bodies, as described by 
yon Kennel, but it does not appear whether or not he examined the species studied 
by the latter author. He also describes and figures the rod-like bodies in the 
epidermis as lying within the epidermic cells, instead of between them, although he 
admits their origin in ‘“‘ gewissen dem Mesenchym eingelagerten Zellen.” It seems 
highly improbable that the rods should originate within one cell and then migrate. 
into another, and I must conclude that Jijima is mistaken in this respect, and that 
the rod-like bodies lie between the epidermic cells in the fresh-water Planarians 
exactly as in the terrestrial forms. Timally, this author comes to the conclusion that 
the rod-like bodies (Ihabditen) are not discharged from the body, a conclusion 
directly opposed to what I believe to be the usually accepted opinion, and to my own 
observations on Geoplana. 
Von Graff (9) gives a very full account of the rod-like bodies, or rhabdites, in the 
Rhabdocelida, for which I must refer the reader to his monograph. He comes to the 
conclusion that in all Rhaddocelida the rod-like bodies, where such occur, originate m 
parent cells in the connective tissue of the body, a view now generally held, and in all 
probability true for all the remaining groups of Planarians. 
I propose now to give an account of my own observations in the case of Geoplana 
spencer. 
In microscopical sections the dorsal surface of the animal, outside the epidermic 
cells, is seen to be covered with a layer of granular, hardened mucous, in which large 
numbers of ejected rod-like bodies, or rhabdites, are imbedded. It is here that the 
structure and form of the isolated rods may best be studied. Figure 24 represents three 
of them as they appear in a tangential section of a specimen preserved in alcohol and 
stained with borax carmine. In this position the rods always appear more or less 
curved or vermiform, a fact which suggests that they possess but little rigidity when 
first ejected ; they sometimes also appear to be very greatly elongated. They are slender, 
cylindrical, and pomted gradually at each end; they are homogeneous in texture and 
stain very deeply with borax carmine. 
In the epidermis itself the rods are found in large numbers wedged in between 
the component cells on the dorsal and lateral surfaces of the animal, while on the 
ventral surface, if they occur at all, they are very scarce. In the epidermis on the 
