Zoological Collections. 149 



in the same time ; but the plant began to droop when it was 

 removed from the jar, and could not be revived. 



Olefiant gas in the quantity of four cubic inches and a-half, 

 and in the proportion of a hundredth part of the air, had no 

 effect whatever in twenty-four hours. 



The Protoxide of nitrogen^ or intoxicating gas, the last we 

 shall mention, is the least injurious of all those we have tried ; 

 indeed it appears hardly to injure vegetation at all. Seventy- 

 two cubic inches were placed with a mignonette plant in a jar 

 of the capacity of 509 cubic inches for forty-eight hours ; but 

 no perceptible change had taken place at the end of that time. 



In all of the foregoing experiments, with the exception of 

 those made with minute proportions of the sulphurous and 

 hydrochloric acid gases, the gas was placed at the bottom of 

 the jars, and the plant on a stage raised nearly to the top of 

 them. It is hardly necessary to add, that comparative expe- 

 riments were also made on plants in jars of pure air. 



It is well know that plants are sometimes affected different- 

 ly by the same agent. Some thrive in situations which are in- 

 jurious to others, and where to all appearance the difference 

 does not depend on the nature of the soil alone. Sir H. Davy 

 found that while some plants grow in an atmosphere of hydro- 

 gen, others are speedily destroyed by that gas. We may 

 hence anticipate that a variety of curious and interesting re- 

 sults would be obtained by experiments directed with this 

 view ; but circumstances have not permitted us to undertake 

 the inquiry. We may observe, however, that of six different 

 species of plants subjected to the action of sulphurous acid, 

 aH of them appeared to be affected by that gas nearly in an 

 equal degree. 



Art. XXV.— zoological COLLECTIONS. 



1. On the appearance of Locusts in the Doab.* By G. Playfair, Esq. 



About the 20th June 1812, a very large flight of locusts was observed 

 hovering about Etawah, which at length settled in the fields east of the 

 town, where they remained some time, and were seen copulating in vast 



" From the Transaction* oftlie Medical and Physical Society of Calcutta^ vol, i. 

 p. 103. 



