98 Dv Gairdner'jj Analysis of 



It will be seen that the Kolpoda cticuUus is again found in 

 both these situations. 



3. In Atmospheric Waters. — The occurrence of infusory ani- 

 mals in this situation became an object of interest ever since 

 Humboldt drew the attention of naturalists to those currents of 

 air which often ascend to the height of 18,000 feet above the 

 earth's surface, and are capable of carrying into the atmosphere 

 many minute bodies which may be deposited on the summits of 

 lofty mountains, or conveyed to distant plains. Not to mention 

 the idea of Spallanzani, of minute infusoria hovering in the at- 

 mosphere, Gleichen's observations of their existence in snow melt- 

 ed in a room, might lead to the supposition of their existence in 

 the atmosphere. 



The burning plains of Africa present peculiar advantages for 

 the decision of the question. During the day, the scorching 

 rays of the meridian sun destroy every trace of life except the 

 lizard ; and during the night, the heavy dews afford atmosphe- 

 ric water in a state of great purity. During Dr Ehrenberg's 

 journey into Africa, he made a point of examining, at almost 

 every resting-place, the dew-drops which deposited themselves 

 so abundantly on their instruments, &c. during the night. Each 

 time he examined from fifteen to twenty drops, so that the ag- 

 gregate number cannot have been short of 800 drops ; but in 

 not one instance has he seen a single living animal. 



With this we conclude our analysis of Dr Ehrenberg's obser- 

 vations, which have already extended perhaps to too great a 

 length. The author, however, was unwilling to give an imper- 

 fect account of these discoveries, which will form so important 

 an epoch in zoological and physiological science. The friend of 

 science cannot, however, help regretting, that while our conti- 

 nental neighbours are adding such important accessions to her 

 domains, not one Briton figures in the annals of Phytozoology ; 

 for we can hardly except from this censure the names of Home 

 and Baer, who have given us a few details on the Vibrio of 

 wheat. I shall only add a single reflection which is naturally 

 suggested by the foregoing subject. When we consider the in- 

 finity of animals with which the material world is filled, their 



