. Cyclopedia de cultures agricoles : une étude des cultures populaires et des méthodes de récolte aux États-Unis et au Canada. Agriculture -- Canada, Agriculture -- United States ; produits de la ferme -- Canada ; produits de la ferme -- United States. Fig. 23. Une plante ceU. L'fieiire montre la rotation de pro- toplasm. (Elodea, ou Anacharis.) Tous les caractères de l'organisme sont une ex- pression de l'activité de son protopla.sm. Aussi longtemps que certains processus chimiques et physiques en lieu en f..e protoplasme nous dire l'organisme est vivant ; quand ces arrêter, nous dire qu'il meurt. Ces substances dans la cellule comme entrer dans le

• Contributeur: Central Historic Books / Alamy Banque D'Images
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. Cyclopedia of farm crops : a popular survey of crops and crop-making methods in the United States and Canada. Agriculture -- Canada; Agriculture -- United States; Farm produce -- Canada; Farm produce -- United States. Fig. 23. A plant ceU. The fieiire shows the rotation of pro- toplasm. (Elodea, or Anacharis.) All the characters of the organism are an ex- pression of the activity of its protopla.sm. As long as certain chemical and physical processes take place in f..e protoplasm we say the organism is alive ; when these stop, we say that it dies. Such substances in the cell as enter into these processes we regard as living ; others, as starch grains, which take no part in them, we regard as dead. The latter may at any time enter into these processes, as when It contains a deeply. starch is converted into sugar, and so become part of the living substance. The transformation of lifeless into living substance, and vice versa, is constantly taking place. Protoplasm may be killed in a variety of ways, as by electric shock, heat, light, mechanical injury or poisonous substances. Within the protoplasm, or cytoplasm, of the cell is contained a body, usually spherical or ellipsoid in shape, called the nucleus, staining substance called chromatin. There is abundant evi- dence that the heredi- tary characters, those handed down from par- ent to offspring, are somehow bound up in^ , the chromatin, and'(' that it is the union of -^ chromatin from both parents in the act of Fig. 24. common cell forms. The fertilization which '^''''s an- tiiirkeue.i at the ., „... angles, forming slrengthen- CaUSeS the offspring to jng tissue. This kind of tis- partake of the char- ^ue is known as collenchyma acters of both. It has ^^"^^ ^• been demonstrated that if the offspring receives protoplasm from both parents but chromatin from only one, it shows the characters of only that one. The division of the cell is accompanied by a division of the nucleus, which may be either direct (ami