THE EPITHELIUM OF) THE, sO-CALEED MIDGUT 
OF’ THE TERRESTRIAL TSOroDps: 
J. PLAYFAIR MCMURRICH. 
THE ease with which preparations may be obtained, and the 
large size of the constituent cells have brought it about that 
the epithelium of the so-called midgut of the terrestrial Isopods 
has not unfrequently been the subject of observation. From 
its cells, within recent years, the Belgian school of cytologists 
have endeavored to deduce the structure of the nucleus and the 
cytoplasm, and it has also figured largely in the discussions on 
the occurrence and significance of amitosis. Still more recently 
Ryder and Miss Pennington have described the occurrence of 
nuclear conjugation in the intestinal epithelium of Porcellio, 
and it was the appearance of this paper that especially aroused 
my interest in the tissue, although my attention had already 
been directed to it by what I had seen of it during the progress 
of my studies on the embryology of the Isopods. 
r. 
My observations have been confined mainly to terrestrial 
Isopods, one species of each of the genera Armadillidium, Por- 
cellio, and Oniscus forming the principal sources from which 
my material was obtained. Preparations of the intestine of 
Idotea robusta were also made, but beyond this I have made 
use, so far as the present paper is concerned, of no other 
marine or aquatic forms. 
The simplest method of obtaining the material is to immerse 
an animal in fluid and, inserting a needle into either extremity 
of the body, pull it to pieces. The “midgut” usually breaks 
just behind the region where the liver czeca communicate with 
the digestive tract, and with very little further trouble it may 
be isolated almost in its entirety. Ifa surface preparation were 
required, the intestinal contents, usually present in animals 
