as to produce any injury.  Indeed, it has been claimed that their presence in the seed in small quantities is a necessity for the proper sprouting of the seed.  It has been claimed that their growth tends to soften the food material in the seed, so that the young seedling can more readily absorb it for its own food, and that without such a softening the seed remains too hard for the plant to use.  This may well be doubted, however, for seeds can apparently sprout well enough without the aid of bacteria.  But, nevertheless, bacteria do grow in the seed during its germination, and thus do aid the plant in the softening of the food material.  We can not regard them as essential to seed germination.  It may well be claimed that they ordinarily play at least an incidental part in this fundamental life process, although it is uncertain whether the growth of seedlings is to any considerable extent aided thereby.

The silo.

In the management of a silo the farmer has undoubtedly another great bacteriological problem.  In the attempt to preserve his summer-grown food for the winter use of his animals, he is hindered by the activity of common bacteria.  If the food is kept moist, it is sure to undergo decomposition and be ruined in a short time as animal food.  The farmer finds it necessary, therefore, to dry some kinds of foods, like hay.  While he can thus preserve some foods, others can not be so treated.  Much of the rank growth of the farm, like cornstalks, is good food while it is fresh, but is of little value when dried.  The farmer has from experience and observation discovered a method of managing bacterial growth which enables him to avoid their ordinary evil effects.  This is by the use of the silo.  The silo is a large, heavily built box, which is open only at the top.  In the silo the green food is packed tightly, and when full all access of air is excluded, except at its surface.  Under these conditions the food remains moist, but nevertheless does not undergo its ordinary fermentations and putrefactions, and may be preserved for months without being ruined.  The food in such a silo may be taken out months after it is packed, and will still be found to be in good condition for food.  It is true that it has changed its character somewhat, but it is not decayed, and is eagerly eaten by cattle.

We are yet very ignorant of the nature of the changes which occur m the food while in the silo.  The food is not preserved from fermentation.  When the siloxis packed slowly, a very decided fermentation occurs by which the mass is raised to a high temperature (140 degrees F. to 160 degrees F.).  This heating is produced by certain species of bacteria which grow readily even at this high temperature.  The fermentation uses up the air in the silo to a certain extent and produces a settling of the material which still further excludes air.  The first fermentation soon ceases, and afterward only slow changes occur.  Certain