74 NATURALISTS’ ASSISTANT. 
for laboratory purposes. Its construction is readily seen from 
fig. 27. It consists of a shallow tray with a series of steps, 
the bottles being held in place by rods running along the case. 
When a row is not full, the vials are fastened by a wedge. 
This form may stand on the laboratory table or can hang 
against the wall as desired. They can also be hinged to- 
gether in pairs, labelled and placed on shelves, 
