MAGNIFYING POWER. 



[ 411 ] 



MARATTIACE^. 



ammonia in small quantities at a time ; the 

 penniform crystals by adding excess of solu- 

 tion of ammonia to veiy dilute solutions of 

 the phosphate of ammonia and sulphate of 

 magnesia ; and the feathery forms by adding 

 excess of ammonia to urine. The prismatic 

 crystals form a beautiful polarizing object. 



Sulphate of magnesia (Epsom salt). When 

 crystallized upon a slide from an aqueous 

 solution, the prisms of this salt movmted in 

 balsam, form an interesting polarizing object; 

 they are also analytic. 



tJrate of magnesia. See Urates. 



BiBL. Thatof Chemistry, ANIMAL, and 

 Phil. Mag. 1852. iii. p. 3/3. 



MAGNIFYING POWER.— The method 

 of determining the magnifying power of a 

 microscope is given under Measurement. 



MAHOGANY.— The wood of various 

 species of Swietenia (Nat. Ord. Cedrelacese). 

 Cross sections of this well-known wood 

 form good objects for showing the structure 

 of Wood with low power. 



MAIZE. — Indian corn, Zea Mays, L. — 

 One of the family of Grasses producing 

 seeds used as corn. The seeds, or rather 

 caryopses, ai'e remarkabl}" firm, being of a 

 horny texture in the outer part of the sub- 

 stance, while the central mass is more or less 

 brittle and soft. The solidity of the grain 

 results from the outer cells of the albumen 

 being densely filled with starch-grains (PI. 

 36. fig. 3), which, by pressure, assume a 

 parenchymatous form and cohere together 

 firmly. In the centre they are loosely 

 packed in the cells, and then are of rounded 

 forms (fig. 5). Figs. 1 to 4 represent suc- 

 cessive stages of development of the starch- 

 grains in the protoplasmic mass, originally 

 filling the cells but finally almost wholly 

 displaced. See Starch. 



MALACOSTOMUM, Werneck.— A 

 genus of Rotatoria. 



The (three) species correspond to Notom- 

 matce without teeth, but require fm-ther exa- 

 mination. 



BiBL. Werneck, Ber. d. Berl. Jkad. 1841. 

 p. 377. 



MALPIGHIAN BODIES. See Kidney. 



MANDIOC or MANIHOT. See Cas- 

 sava. 



MANILLA HEMP.— One of the most 

 delicate of vegetable fibres used for textile 

 fabrics, yielded by the liber of the fibro-vas- 

 cular bundles of Musa textilis, a kind of 

 banana common in the Philippine Islands 

 (PI. 21. fig. 7). It is manufactvu-ed into 

 " Manilla handkerchiefs " and " Manilla 



scarfs," consisting of a delicate muslin. 

 These are often erroneously stated to be 

 made of the fibre of some kind of Pine-apple. 

 See Textile Substances. 



BiBL. Hooker's Journal of Botany, vol. i. 

 28. 1849. 



iviARANTACEiE.- A family of Monoco- 

 tyledonous Flowering plants, to which belong 

 the true West Indian arrow-root plants (see 

 Arrow Root), and the Tous-les-mois 

 plants, species of Canna. These sub- 

 stances consist of the starch (PI. 36. figs. 18 

 & 25) obtained from the tuberous rhizomes 

 of the plants (see Starch). 



MARATTIA, Swartz.— The tjq^ical genus 



Fig. 446. 



Fig. 447. 



Marattia 

 Fig. 446. Side view of a sorus. 



ig- 



Fisr. 447. Indusium with the sorus removed. 



Magnified 12 diams. 



of Marattiaceous Ferns. Exotic (figs. 446 



& 447). 



MARATTIACEiE.— A family of Ferns, 

 approaching the Polypodiacese in general 

 habit, but more resembling the Ophioglos- 

 sacese in their sporanges, which are destitute 

 of an annulus, and often so fused together 

 as to look like a multilocular sac. 



Genera. 



I. Angiopteris. Sporangia in two rows 

 near the apex of transverse veins, distinct, 

 forming linear sori, opening by a slit on the 

 outer side. No indusium. 



II. Kaulfussia. Sporangia placed on the 

 anastomoses of the veins, radiately connate, 

 forming roundish sori, opening by a sht at 

 the apex. 



III. Marattia. Sporangia in two rows 

 near the apex of transverse veins, connate, 

 forming oblong sori, gaping transversely by 

 a vertical slit. Indusia connate with the 

 sori (figs. 446, 447). 



IV. Eupotium. Sporangia as in Marattia, 

 but pedicellate. 



V. Dancea. Sporangia in two rows, near 

 the transverse veins, connate into linear sori, 

 opening by a pore. Indusia superficial, en- 

 circling the sori (fig. 159. page 188). 



