PRESERVING VEGETABLES AND FRUIT 167 



rate a pale green pigment which imparts a beautiful blue fluorescence to the 

 medium. 



All these bacteria are exclusively aerobic, i.e. oxygen is essentially necessary 

 to their development. This needful gas obtains access from outside by passing 

 through the eggshell, which is well known to be permeable thereto, since other- 

 wise the development of the embryo chicken could not proceed. This necessity 

 for air on the part of the egg-putrefying Schizomycetes supplies the explanation 

 of the practice currently employed for preserving eggs, viz., by simply immersing 

 them in milk of lime, which not only excludes air, but also by its disinfectant 

 properties acts on the organisms present on the eggshell and ready to penetrate 

 into the interior, killing some and restricting the development of others. 



The aforesaid bacteria perish within the space of two days when exposed to 

 temperatures above 40 C., but at lower temperatures and in damp air they 

 develop rapidly. Bearing these facts in mind, eggs could be preserved by keeping 

 them for one or two days at 50 C. and then storing them in a dry place, were 

 it not that the quality is thereby depreciated. If, then, steeping in milk of lime 

 is not determined upon, the eggs can be preserved by coating them with lacquer 

 or varnish after a careful cleaning. 



That bacteria penetrate through the unbroken eggshell has contrary to an 

 opposite opinion expressed by Gayon been placed beyond doubt by the ex- 

 haustive researches of Zorkendorfer. WILM (I.) showed that pathogenic bacteria 

 are also capable of so doing, cholera bacilli being found, in his experiments, to 

 penetrate to the interior of the egg within fifteen to sixteen hours. PIORKOWSKI 

 (I.) arrived at a similar conclusion with regard to typhus bacilli. On this account 

 none but clean chaff, free from pathogenic organisms, should be used for packing 

 eggs- 



Bacteria are not to blame in all cases where eggs become spoiled during 

 storage, but sometimes higher fungi (Eumycetes) come into play, penetrating 

 the shell and growing freely in the interior. Further particulars on this point 

 will be found in the second volume, in the chapter dealing with Iformodendron 

 cladosporioides. 



133. Desiccating and Preserving- Vegetables and Fruit. 



In contradiction of the erroneous assumptions of M. GALIPPE (I.) and 

 H. BERNHEIM (II.), it has been shown by E. LAURENT (III.), A. FERNBACH (I.), 

 and H. BUCHNER (VIII.) that apart from the exceptions to be considered in 

 chapter xxxiii. the cells and cellular tissues of the higher plants are, whilst in 

 a healthy condition, free from fungi. In the preservation of vegetable food- 

 stuffs it is, therefore, merely a question of the destruction, or restriction of 

 development, of the germs of extraneous origin inhabiting the surface. The 

 oldest process for attaining this object is that of drying, and this is practised 

 more particularly on certain fruits. In warmer regions the rays of the sun 

 suffice, e.g. in the case of raisins and figs, but in colder climes recourse must be 

 had to artificial warmth, and, consequently, so-called kilns or drying ovens are 

 employed, wherein hot air at a temperature of 60^-65 C. is allowed to stream 

 over the fruit. American desiccated apples and Bosnian and Servian prunes 

 are prepared in this way. A description of the individual systems of kilns for 

 this purpose cannot be entered upon here. The dried fruit still contains a con- 

 siderable proportion of moisture (some 30 per cent.) and at least the same 

 amount of sugar : about 30 per cent, in the case of pears, some 40 per cent, in 

 apples and damsons, 50 per cent, in figs, and 60 per cent, in raisins. From i to 

 3 per cent, of free acid is also present. Only some of the organisms present on 

 the fruit are killed by drying, but the development and decomposing action of 



