{ Carbon dioxide is taken in by the plant and { oxygen is liberated. { Starch is formed as a result of the metabolism, { or chemical change. { The process takes place only in green plants, Starch formation { and in the green parts of plants, that is, or Photosynthesis. { in the presence of the chlorophyll. { (Exception in purple bacterium.) { The process only takes place under the { influence of sunlight. { It is a building-up process, because new plant { substance is formed. { Oxygen is taken in by the plant and carbon { dioxide is liberated. { Carbon dioxide is formed as a result of the { metabolism, or chemical change. { The process takes place in all plants whether Respiration. { they possess chlorophyll or not. { (Exceptions in anaerobic bacteria). { The process takes place in the dark as well as { in the sunlight. { It is a breaking-down process, because { disintegration of plant substance occurs. CHAPTER XII. GROWTH. By growth is usually meant an increase in the bulk of the plant accompanied generally by an increase in plant substance. Among the lower plants growth is easily studied in some of the fungi. =240. Growth in mucor.=—Some of the gonidia (often called spores) may be sown in nutrient gelatine or agar, or even in prune juice. If the culture has been placed in a warm room, in the course of 24 hours, or even less, the preparation will be ready for study. =241. Form of the gonidia.=—It will be instructive if we first examine some of the gonidia which have not been sown in the culture medium. We should note their rounded or globose form, as well as their markings if they belong to one of the species with spiny walls. Particularly should we note the size, and if possible measure them with the micrometer, though this would not be absolutely necessary for a comparison, if the comparison can be made immediately. Now examine some of the gonidia which were sown in the nutrient medium. If they have not already germinated we note at once that they are much larger than those which have not been immersed in a moist medium.