. The cytoplasm of the plant cell. Plant cells and tissues; Protoplasm. Guilliermond - Atkinson — 72 — Cytoplasm that the great majority of cytologists are at present in agreement in recognizing that the plastids of Schimper are derived from elements presenting the same forms as those of the chondriosomes. The life history of the chondriosome in phanerogams will now be studied in detail by first following the formation of chloroplasts. As the phenomena are the same in all buds, it is sufficient to choose a single example. The most favorable, because of the dis- position of foliar primordia, is
. The cytoplasm of the plant cell. Plant cells and tissues; Protoplasm. Guilliermond - Atkinson — 72 — Cytoplasm that the great majority of cytologists are at present in agreement in recognizing that the plastids of Schimper are derived from elements presenting the same forms as those of the chondriosomes. The life history of the chondriosome in phanerogams will now be studied in detail by first following the formation of chloroplasts. As the phenomena are the same in all buds, it is sufficient to choose a single example. The most favorable, because of the dis- position of foliar primordia, is the bud of Elodea canadensis, first investigated by Lewitsky. Afterward, it was the object of inten- sive study for us and our reports were confirmed by Friedrichs. If a longitudinal section of a bud of Elodea canadensis be ex- amined after being fixed by Regaud's method \ ., -2is« ^ ,^^ (fixation by a mixture of potassium bichromate 'l{"ly^<^^^'' ^^^ formaldehyde, and staining with iron Cv^V ^i!S^S>'=k Vx- those foliar primordia which are about 160/i long. In those measuring about 200/i in length, the chondrioconts form little swellings on their long axes in which a small starch grain is sometimes elaborated. As this grain is not stained by iron haematoxylin, it looks like a vesicle. Starch grains thus formed are only transitory and soon disappear. The swellings then gradually separate by rupture of the slen- der portions between them. They increase in volume and, in ma- ture cells, take on the appearance of large, rounded or ovoid, chloro- plasts about 4-8)11 in diameter. These are distinguished from the chondrioconts, from which they arose, by the modification which they have undergone in their chemical qualities which gives them a special resistance. They are preserved by all the fixatives which destroy the chondriosomes. Henceforth these chloroplasts often elaborate large starch grains. During the differentiation just described, the granular mito- chondria
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