Nuchdruck verboten, 
Übersetzungsrecht vorbehalten _ 
Opalina mitotica. 
By 
Maynard M. Metcalf, Ph. D., 
Professor of Zoology, Oberlin College. 
With plate 2 and 1 figure in the text. 
In this very interesting species the nuclei rest in a mid-mitotie 
eondition instead of in the network or granular condition as in all 
other known animals and plants. These Opalinas were discovered 
by Professor J. H. Powers of the University of Nebraska. He has 
sent me a half-dozen beautifuly prepared slides of these parasites 
and asks me to describe them, making only the condition that the 
species be not named for him. 
In answer to my questions Professor Powers’ daughter, Miss 
H. H. Powers, writes: „They (the Opalinas) were taken from the 
rectum and large intestine of Amblystoma tigrinum late in 
the fall. The specimens from which they were obtained were all 
young animals that been fed in water for a month or more on 
chopped liver. During the fall a few of the animals so kept usually 
die unless taken from the water at this their period of hibernation. 
They seem morely to get too lazy to rise to the surface for air. It 
was from such animals as these, taken a few hours after death, that 
the Opalinas were obtained by removing the digestive canal and 
opening it in normal salt solution. They were washed out in this 
solution together with the contents of the rectum. In this normal 
salt solution the Opalinas were eradually isolated by tilting and 
shaking the dish in various ways until they could be drawn off with 
a pipette and placed in the killing fluid. 
