M. De la Hive on the Formation of Hail. 299 



contains being much less ; and since at the moment of their for- 

 mation the temperature is not lower than in summer, they must 

 clearly condense a smaller quantity of water upon their surface, 

 since they encounter less in their passage : they then form what 

 we call hoar -^r OS t (gresil). 



We believe, therefore, that hail is formed in the most elevat- 

 ed regions of the atmosphere ; where we besides know, from the 

 appearance of halos, that small crystals of ice are often floating. 

 The cloud which carries these small nuclei of hailstones on its 

 upper surface descends obliquely towards the earth through the 

 combined effect of its weight and of the dominant wind. In 

 proportion as it descends, the hailstones increase in size, or di- 

 minish and are dissipated, according as they meet in their course 

 clouds, or a dry atmosphere. In the former case, the cloud 

 which conveys them becoming always more and more weighty, 

 at length descends lower than all the others, as has been often 

 remarked, and finally disperses itself upon the ground. 



We shall not attempt at present to develope more in de- 

 tail the ideas which we have now expressed. We should even 

 have waited till a greater number of observations than those 

 which we have already made had furnished us with a more solid 

 groundwork, had not the publication of M. Lecoq presented a 

 favourable occasion for their publication; 



New Researches on the Organic Elements, and intimate Struc- 

 ture of Animal Bodies By G. R. Trkviranus. Bremen, 

 1836. * 



Having detailed in the preface the various expedients which 

 were employed to render the microscopical examination of the 

 tissues free from error, the author proceeds to detail in the first 

 chapter his observations on the intimate structure and ultimate 

 organic elements of cellular membrane. The result at which he 

 arrives is, that in the vertebrated animals, cellular membrane is 

 composed of cylinders or tubes, which he terms elementary cy- 



• The above analysis of Treviranus's very interesting volume, with the 

 observations, are from the last number of the Dublin Medical Journal, com- 

 municated to that work by Dr Graves. 



