28 BULLETIN OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 4, NOS. 1-2. 



closed pipette and kept for an extended time at an exhaustion 

 of about 300 mm., a number of small metallic, bluish-purple, 

 spurred and acidulated scales and needles appear in the upper 

 bulb of the tube. These lamellae appear pink by transmitted light. 

 Although b}' their luster and volatile character they suggest iodine, 

 they give no test for this element, and are probably a polymerisa- 

 tion product, as they increase in number with time, even when 

 kept at the ordinary pressure. 



Unfortunately, although our Spirobolns were very active at 

 first — on one occasion a large specimen ejected a decided stream 

 a distance of ten inches — they soon showed signs of weakening, 

 and after about ten extraction, which gradually diminished in 

 amount during the four months of experiment, their glands re- 

 fused to reproduce their secretion, although the animals seemed 

 otherwise in good condition, and we were forced to discontinue 

 the interesting study. 



Although Loew suggested pyridine it was with the under- 

 standing that this odor might have come from the German alcohol 

 used as the preservative. This must obviously be its source, as 

 Spirobolus has quite a different odor. The facts brought forth by 

 Dr. Cook as to the action of the air we have duplicated during 

 our tests, and these can all be explained upon the idea of saponi- 

 fication. It is not the final composition that is efifective as the 

 repelling agent, as he has suggested, but the condition that 

 obtains just before decomposition. The unstable nature of the 

 secretion gives it great reducing power, as can be shown with 

 alkalinated silver iodide. Its staining effects recall the secretions 

 of Brachynus, Platynus, and their related forms among the 

 beetles, which insects Julus greatly resembles in smell, but in addi- 

 tion to the staining principle these Carabidse produce formic and 

 butyric acids, so the secretions cannot be identical. 



Experiments zvith Ants. 



A. The relative Amount of Formic Acid present in different 

 Species. 



It has long been known that certain species of ants, e. ;,>■., 

 Formica and Lasius, secrete a considerable amount of free formic 

 acid. This is stored up in the sac which contains the acid part 

 of the stinging fluid in those species of Ants which have well- 

 developed stings, while in those devoid of stings it is retained in 

 a special sac in the posterior part of the abdomen. The following 

 experiments were conducted with a view towards determining' 



