126 
Psyche 
[December 
ence in the method of procedure of different species at this 
stage than at any other. 
The limnephilid which we studied builds a case of the “log 
cabin” type, that is of small pieces of plant material placed 
transversely with respect to the long axis of the case. In 
studying the animals it was customary to push them out of 
their cases with a blunt needle and place them in a small dish 
with water and materials with which they might build a case. 
All of the materials mentioned in the accounts which follow 
which would not usually sink in water (e.g. paper and pine 
needles) were kept in it until they became waterlogged 
before being used. 
The typical case-building procedure as observed in the 
laboratory is as follows. A larva, pushed from its case, is 
placed in a dish containing plant debris similar to that ordi- 
narily used in its case. It crawls about for a time, then 
commences to gather bits of plant material beneath itself, 
holding them partly with its legs and partly by curling its 
abdomen downward. Soon, by employing a salivary secre- 
tion, it joins to one another the plant fragments that have 
been collected. In this way an irregular chain is formed 
composed of the pieces of building material. When the 
chain is of sufficient length the larva holds one end of it with 
the legs of one side and with a leg of the other side reaches 
around in back of itself for the free end of the chain. This 
is then drawn around to the ventral side and the two ends 
joined. The procedure is similar to that followed by a person 
in putting on a belt : he holds one end in front of himself and 
with his other hand reaches around in back for the free 
end which is then brought forward and fastened. In his 
account of the case-building of a caddis-worm, Limnephilus 
flavicornis, Gorter refers to this wrapping of the girdle 
around the larva in forming a “provisional case”. He does 
not, however, describe the procedure. 
The girdle formed of the chain of loosely-joined pieces 
constitutes the foundation on which the first part of the case 
proper is built. This girdle is held by the larva at the level 
of the metathorax and pieces of plant material are added, 
one at a time, to the forward edge. 
The method of building the case from this point on has 
been described by others (See Lloyd 1921, Gorter 1929) , and 
