CHXOKOPLAST. 679 CHMIELNICKI. tion of light by six to ten ci'll-laycrs is so com- plete that neither chlorophyll nor chloroplast is developed. Chloroplasts originate from preex- ihtent structures of the same kind. Unspecial- ized protoplasmic organs known as plastids (q.v. ) multiply by direct division as the cells di- vide. Later those plastids in the siperficial cells may diflorentiate into chloroplasts, which also may increase by direct division ; those in storage organs may become leucoplasts (q,v.) ; or in appropriate regions they may form chromojjlasts (q.v.) ; or the chloroplasts may later be trans- formed into chromoplasts. The form of chloroplasts is quite various in some of the algse. In Spirogyra there are one to several ehloi'oplasts. Each is ribbon-like, with an irregularly toothed edge, somewhat depressed and thicker along the median line (thus trough- like) and spirally coiled in the protoplasm near CHI.OBOPLA8T8. a, Lemna. with cliloroplasts against the vertical walls ; ?>, Spirogyra^ the two chloroplastt consisting of spiral bands. to the cell-wall. In Mougcottia the chloroplast is single and plate-like, occupying the axis of the cell. In Zygneraa there are two chloroplasts, each an irregular mass, with radiating arms reaching to the periphery. All these chloroplasts are peculiar in having one or more pyrenoids (q.v.) imbedded in them. In species of Antho- eeros and Selaginella each cell contains a single irregular chloroplast. But in most algae and mosses and in all the higher plants the chloro- plasts are several or many in each cell, and have a somewhat flattened globoid or ovoid form. The structure of the chloroplast, like that of other protoplasmic organs, is not definitely known : but it appears to be vacuolate, i.e. to consist of a firmer colorless portion inclosing many minute spaces filled with clilorophyll : but just how the latter is related to the colorless portion, and whether dissolved or not, is not satisfactorily determined. The chloroplasts are capable of moving about the cell. Mien the protoplasm is rotating, the chloroplasts are swept along with it ; but they are capable of independent creei)ing. When a leaf of sorrel, for example, is exposed to diffuse light, the chloroplasts arrange themselves on the best illuminated sides (top and bottom) with their broad sides turned to the light. This posi- tion is known as epistrophe. In direct sunlight they pass to the side walls, standing edgewise to the light, a position known as light apostrophe. A somewhat similar position is assumed in pro- longed darkness (dark apostrophe), the chloro- plasts accumulating also on the bottom of the cell. Photo3Tithesis depends wholly upon the chloni])last and its associated chloropliyll. The dcculorizeil chloroplast is imable to form carbo- hydrates, and chlorophyll separated from the chloroplast is equally functionless. See Etioun; Photosynthesis: JIovement; Pkotoplasm. CHLORO'SIS (Xco-Lat., from Gk. X"P^C, chloros, greenish-yellow). A peculiar form of anaemia, common in j'oung women, and connected with the disorders incident to the beginning of menstruation. It has been called the green sick- ness, from the peculiar dingy greenish-yellow hue of the complexion in some patients. The disease is- atlended with very great debility, and often with brcatlilessness, palpitation, and other symp- toms, including a perverted appetite, which leads the girl to eat chalk, slate pencils, etc. Chlorosis is curable in a large proportion of cases. The principal means to be employed are rest, out-of- door air, moderate exercise, a selected diet, proper clothing, iron, and arsenic. CHLOROSIS. A diseased state of plants, in which a sicklj- green or greenish-yellow color takes the place of the natural color. Sometimes only a particular shoot is allected by it, but very generally the whole plant : and it seems to de- pend upon causes which render the plant alto- gether unhealthy, the pallid appearance being merely symptomatic, and not only the formation of chlorophyll, but all the functions of vegetable life being languidly and imperfectly carried on. There seems to be considerable evidence that chlorosis is largely due to malnutrition of the plant, but the specific cause is not known. Plants affected by this disease are often to be seen among crops generally healthy; but whole crops of grain, potatoes, etc., sometimes perish from it, or are much diminished in value. Fruit-trees also suffer from it. A severe attack of chlorosis on fruit-trees in a certain region in England is re- corded where lime was abimdant in the soil, and hence the attack could not be attributed to a lack of lime, as is sometimes claimed. A mixture of nitrate of potash, superphosphate, and iron sul- phate was given the trees as a fertilizer, with excellent results. In France grapes arc subject to chlorosis to a great extent, and good results are reported to have followed washing the vines and fertilizing them in winter or early spring with An iron sulphate solution. CHMEL, Kmel, Joseph (1798-1858). An Austrian historian, born at Olniiitz. He was ap- pointed in 1S46 vice-director of State archives in Vienna. His works include Die Hanilschriften tier kiiiserlich-l;6)iiglichen Hofhibliothek zu Wien (1840-41): Geschichte Kaiser Friedrichs IV. (1840-4.,); and Vrkunden, Brief e und Akten- stiirki- tin- flcsrhiclile ilaximiliari I. (1845). CHMIELNICKI, KmviM-nits'kf, Bogda?? ( 1.5!l.'MOr>7 ) . The leader of the Cossacks in the great revolt against Poland in the middle of the Seventeenth Century. He belonged to a noble Polish family, and was born in the Ukraine. He won by his bravery a high position among the Cossack tribesmen about the Pnieper. Oppressed by the Poles, the Cossacks rose in insurrection
