THE TRAM-WEAVERS, 59 
single fringed cell, sometimes as a many-celled fringed ball, 
can evidently be classed with none of the other Protista, 
and must be considered as the representative of a new 
independent group. As this group stands midway between 
several Protista, and links them together, it may bear the 
name of Mediator, or Catallacta. 
The Protista of the fifth class, the Tram-weavers, or 
Labyrinthulee, are of a no less puzzling nature; they were 
lately discovered by Cienkowski on piles in sea water (Fig. 
13). . They are spindle-shaped cells, mostly of a yellow- 
Fie, 13.— Labyrinthula macro- 
cystis (much enlarged). Below 
is a large group of accumulated 
cells, one of which, on the left, 
is separating itself; above are 
two single cells which are gliding 
along the threads of the reti- 
form labyrinth which form their 
“ tramways.” 
ochre colour, which are 
sometimes united into a 
dense mass, sometimes 
move about in a very 
peculiar way. They form, 
in @ manner not yet explained, a retiform frame of en- 
tangled threads (compared to a labyrinth), and on the 
dense filamentous “tramways” of this frame they glide 
about. From the shape of the cells of the Labyrinthulez we 
might consider them as the simplest plants, from their 
motion as the simplest animals, but in reality they are 
neither animals nor plants. 
