6 3 8 



THE POPULAR SCIENCE MONTHLY. 



in the sparrow, offensive to many persons. 

 Item, nervous invalids are fretted and an- 

 noyed into positive illness by the unceasing 

 noisiness of these birds. 5. "They (the 

 sparrows) have at present practically no 

 natural enemies, nor any check whatever 

 upon limitless increase," though, even with 

 the most unobjectionable species of birds, 

 a check would be desirable. And now what 

 course must we adopt in order to abate this 

 sparrow nuisance ? for abate it we must, or 

 else the sparrows will eat us all out of house 

 and home. Dr. Coues's recommendations 

 on this head are: 1. Let the birds shift ^or 

 themselves. Take down the boxes and all 

 special contrivances for sheltering and pet- 

 ting the sparrows ; stop feeding them ; stop 

 supplying them with building-material. 2. 

 Abolish the legal penalties for killing them. 

 " Let boys kill them if they wish. Let them 

 be trapped and used as pigeons or glass 

 balls in shooting-matches among sports- 

 men." This last recommendation shows 

 very plainly that Dr. Coues has lost all pa- 

 tience with the sparrow. For ourselves, we 

 hope the evil will be checked by some dif- 

 ferent means. 



Agencies of Nitrification. The research- 

 es of Schloesing and Miintz in nitrification 

 have resulted in the very important discovery 

 of a nitrifying organism analogous to the 

 ferment organism of yeast. The evidence 

 of the existence of a nitrifying organism is 

 found in the fact that the process of nitrifi- 

 cation, however actively it may be going on, 

 is immediately stopped when chloroform-va- 

 por is introduced, the effect being precisely 

 the same as that seen when chloroform-va- 

 por comes in contact with yeast. Again, 

 these authors find that when nitrification 

 has thus been stopped for several weeks, 

 the addition of a small quantity of a nitrify- 

 ing body will start the process again. They 

 also find that the temperature of boiling 

 water is sufficient to destroy all power of 

 nitrification, and that soil which has once 

 been heated to that point produces, in air 

 free from germs, carbonic acid and ammo- 

 nia, but no nitrates. If, however, this soil 

 is moistened with water containing a little 

 untreated soil, the production of nitric acid 

 again commences. This new theory, as we 

 learn from Nature, has been tested in Eng- 



land with results fully confirmatory of the 

 views set forth by Schloesing and Miintz. 

 Hence the evidence is very strong that the 

 nitrates in soil owe their origin to oxida- 

 tion brought about by living organisms. 



How Ants distinguish Each Other. 



Ants are eminently pugnacious, and oppos- 

 ing hosts belonging to the same species may 

 any day in summer be seen waging inter- 

 necine wars on one another. But how are 

 they able to distinguish friend from foe in 

 their tumultuous strife ? Mr. McCook, mem- 

 ber of the Academy of Natural Science of 

 Philadelphia, has made sundry experiments 

 which appear to show that difference of odor 

 constitutes the means of discrimination. 

 Of course, it is not possible to demonstrate 

 this hypothesis directly by showing the ex- 

 istence, either of distinct odors, or of dif- 

 ferent intensity of odor, in opposing hosts. 

 But, if we introduce into the scene of conflict 

 some strong foreign odor which shall oblit- 

 erate the odors peculiar to the two groups of 

 combatants, we may deprive them of the pow- 

 er of telling friend from foe, and make them 

 live together in harmony as one community. 

 Such was the idea which occurred to Mr. 

 McCook. He collected a number of comba- 

 tants, and placed them, friend and foeman, 

 together in a glass jar upon some soil. The 

 battle was continued, and when it was again 

 at its height a pellet of paper saturated 

 with cologne-water was introduced into the 

 jar. The effect was instantaneous. The 

 ants showed no signs of pain, displeasure, 

 or intoxication; indeed, some ran freely 

 over the paper. But in a very few seconds 

 the combatants had unclasped mandibles, re- 

 leased their hold of enemies' legs, antennae, 

 and bodies, and after a momentary confu- 

 sion began to burrow galleries in the earth 

 with the utmost harmony. The quondam 

 foes dwelt together for several days in unity 

 and fraternity, amicably feeding, burrowing, 

 and building. Another experiment was as 

 follows : A large number of warring ants 

 were placed in a box partly filled with soil, 

 and communicating by a glass tube with a 

 smaller box. The larger box was about ten 

 inches long and eight inches in depth and 

 width ; both boxes had sliding glass cov- 

 ers. Cologne was introduced as before into 

 that end of the box in which the coinba- 



