and on the Organic Bodies contained in Hailstones, Sfc. 161 



used a metallic framework with a screw, by means of which 

 the whole is rendered perfectly air-tight, and the glasses may be 

 pressed nearly into immediate contact, but in most cases this is 

 superfluous. As an instance of its efficiency in preventing all 

 evaporation, I may state that I have preserved vaccine lymph 

 in a fluid state in this manner during more than two months, 

 with merely the assistance of a degree of pressure on the 

 glasses, in the first instance secured by a few turns of wire. 

 This is decidedly the most effectual mode of preserving this 

 substance fit for use at any moment. A few of the same kind 

 of apparatus in the pocket-book will be found most useful 

 companions to the microscopic observer, when the slips of 

 glass in ordinary use are inapplicable. 



Although the existence of organized particles in the upper 

 regions of the atmosphere appears at first very improbable, 

 we shall find that several facts exist which much decrease this 

 apparent improbability, and even some that appear to corro- 

 borate this statement. M. Boussingault has found that organic 

 matter may invariably be detected in the atmosphere. It is true 

 that his experiments have been confined to the loweralmosphe- 

 ric strata, and it would be very desirable to ascertain whether 

 they hold good for those which are several thousand feet above 

 the sea. The same may be detected in rain-water ; and what 

 is still more to the point, I find that M. Girardin {Academic 

 des Sciences, April 1834) has detected in the water resulting 

 from the fusion of hailstones, "a strongly azotized organic 

 matter, and also lime and sulphuric acid without any trace of 

 ammonia being present." The frequent vegetations in snow 

 show at what a low temperature the vital principle may be 

 sustained. The red and green appearance assumed by it has 

 been found to be produced by the Hcematococcus nivalis and 

 the Protococcns viridis, as these plants have been termed, and 

 which are probably the same species at different periods of 

 growth, which have been found to penetrate many inches 

 below the surface of the snow. These vegetations are found 

 under the microscope to consist of minute globules, some 

 green and transparent, about the size of 0""""()I toO'""'-05; 

 others red, generally larger than the former, and frequently 

 arranged in single rows, like the beads of a necklace, adherent 

 together. The globules are found of all intermediate tints 

 between the green and the red, and likewise others of larger 

 dimensions of a red colour, about 0"""'05 to the 0'"'"'055, 

 which have a more compound structure, as within them are 

 seen several granules or smaller globules, which was not the 

 case in the two former. M. Martens states, that in some of 

 these globules microscopic infusoria may be detected (see 



