COLLECTING. 



61 



nests with two or three chambers respectively, connected by gal- 

 leries. Of course any other design which suggests itself as suitable 

 may be used instead, if desired. Before the plaster has set, a second 

 plate of the same size and shape as the base and previously covered 

 with a film of sweet oil, is pressed down on to the plaster till it 

 forms walls only a few millimetres in height. After the plaster has 

 set, the roof -pane is removed, cleaned and cut into two or more 



/ 



Fig. 53. Small "Santschi" observation nests. 



pieces with a diamond along lines (dotted in the figures) which 

 bisect the short galleries, and then replaced as covers of the cham- 

 bers. The ants can be introduced into the nest by sliding the covers 

 apart a short distance over one of the galleries. The plaster is 

 sufficiently porous to provide for ventilation and a thin slice of 

 wet sponge, or a tuft of wet moss or cotton, placed in one of the 

 chambers will furnish the requisite amount of moisture." Such 



Fig. 54. ' ' Crawley-Lubbock " observation nest. 



nests can be placed on the stage of a compound or binocular micro- 

 scope, and studied under a low objective. 



Crawley has improved on the Lubbock type of nest as follows : 

 " The nest consists of two panes of glass, one foot square, with 

 slips of thick glass, J in. wide, round the edges, so as to form a 

 frame, leaving a space of nearly J in. between the upper and lower 

 glass. On the bottom glass is a layer of plaster of Paris, reducing 

 the interval between the glass panes to J in. The space between 

 is filled with fine earth." The earth should be placed on the layer 



