1316 



PHOTOGRAPHY 



coated with u silver chloride rather than a silver bromide 

 emulsion. The slide is usually faced with a paper mask, 

 so as to include only the desired portions of the picture, 

 and protected by a cover glass. Negatives of any size 

 may be used if a suitable arrangement is provided for 

 reduction. This can readily be arranged by an adapta- 

 tion of the camera-stand illustrated in Fig. 17G8. A pair 

 of light bars are added, running from the top of the 

 plate-glass frame to a support at the other end of 

 the stand, and a piece of heavy muslin or light canvas 

 thrown over this serves to exclude the excess of light. 

 A ground-glass frame is added back of the plate-glass, 

 which latter is removed to give place to a turn-table 

 arrangement, made to take and hold negatives of vari- 

 ous sizes. In practice, the ground glass end is turned 

 toward the strong light, the negative to be used is ad- 

 justed in the turn-table, and the image focused in the 

 camera as usual. The 5x7 size largely used by hor- 

 ticulturists is in just the right proportion for the 

 ordinary lantern plate of American practice, which is 

 HH X i inches. Slides may also be made by contact, if 

 the negative to be used is of suitable size. The familiar 

 4x.5, nv, x:i'< :nid :i'i\- I'i h:nid ,'aiiirra lilm^ arr- oltf-u 

 so usi-(l. Ii.-Mii; |.l:i.',.,l in r.inl.i.-t with a l:,ntri-n lilatr in 



quality. 11' it is ruquircd to make- Umturii-slidus from 

 diagrams, engravings or any positive material, a nega- 

 tive must be first prepared, for making which the verti- 

 cal position of the camera stand (Fig. 1769) is very 

 convenient. 



In making lantern-slidi-s. it is important to learn the 

 proper exposure, for i-rn.rs in .xiMixurc cannot be cor- 

 rected in development t.. any 1,'r. at i\iiiit. The careful 

 worker will expose several plai.'s iii.on the same subject, 

 give all the same development, and act upon the ex- 

 perience thus gained. 



The only work treating specifically of the photography 

 of flowers and trees is a previously mentioned mono- 

 graph in The Photo-Miniature, No'. 13, published by 

 Tennant & Ward, New York. In the same series of 

 monographs is an excellent treatise on the production 

 of lantern-slides (No. 9), and another on modern lenses 

 (No. 1), previously cited, j. Horace McFarland. 



PHOTOSYNTHESIS. The' terra Photosynthesis is 

 di-rivi-d from Greek words signifying "light" and "put- 

 ting together." It is applied to that process by means 

 of which, under ordinary cir.unisiani-i's. green plants 

 build up organic or .•arl.on roniaiiiing compounds. 

 Carbon is the element wlnrh as a r\iU- <lenotes organic 

 substance. It is an ess.ntiai i-onstitneMt of the cell 

 wall, or fiber, and of the protoplasm; likewise of starch 

 and of sugar. Green plants manufacture practically all 

 of the organic matter which may eventually furnish 

 food for plants and animals, so that all life is ulti- 

 mately dppfnrlcnt >ipon thorn. 



Ordinary air contains only about .04 per cent of car- 

 bon dioM,l: y,t tin- mrcTi plant as a rule obtains all of 

 Its carl. on lioin ihr aif. ( 'lilon.phyll and light are abso- 

 lutely . --onii ,1 111 or.l.r that orirtmic snl.sttiiK-e mav be 



nite pla-.nn- 1 s, xvh.W, a ,■ intnonlv o,;,| i„ form. 



Thes.. ,-hlofo|,hyll Ii,.s al.sorl, ra.lianf- lij^ht and thus 



Obtain energy or power to work. This energy cannot be 

 obtained by the common plant in any other way, as by 

 the absorption of radiant heat from a stove. The cell 

 sap absorbs the oarl.on dioxid which has diffused into 

 the leaf ;..( /•,'),/ ;,,/,„/,/ of Pl,i„ls]. tmd Iho .•n.-r-v 



formaldehyde (CHad). i 

 molecules are perhaps ii 

 (CaHiaOs). In this pi. 

 by the water and carix.n 

 organic product, and thi^ 

 This whole process is lal 

 An accumulation of snu 

 further manufacture of 

 suLCar formed is, indeed. 



PHEYNIUM 



cells. The leaf assimilates very rapidly in sunlight, 

 and the snriiln- -n-ai lorined is changed to starch, an 

 insolubh' I I I : III -larch is usually removed from 

 the leaf a I I I Ml. way potassium salts seem to 



be necesvn m I In liiM manufacture of sugar, perhaps 

 aiding in llie condmsation changes. 



It is probable that no plant containing chlorophyll in 

 genetic connection with its protoplast remains long 

 entirely ina.-tivr iti assimilation, when illuminated. 



'I'll- ''1 ' '' ! t' '1 ; ' . ri um embraces the colors which 



a" I ; I . . ,1 in the activity of the cbloro- 



|! h, : I i i \nthesis is moat rapid under 



III :,;,!;. >•; i'i rature and food supply which 



lii-t -iiiiiiuau ^i.'A ill. The process is more rapid, how- 

 ever, when the amount of carbon dioxid in the air is 

 slightly increased. The presence of other coloring mat- 

 ters, such as brown and red, in the assimilating organs 

 does not mean that chlorophyll is absent, and that other 

 substances may replace it. Chlorophyll may be present 

 but veiled by a more prominent color. It is improbable 

 that any other coloring matter besides chlorophyll and 

 a related substance, etiolin, is effective in carbon dioxid 



i'hot. .synthesis may be inhibited by too intense light, 

 l.y . \t limes of temperature, and by deleterious chemical 

 agents. It ceases immediately in darkness, and is very 

 leehle in weak light. 



The results of photosynthetic activity may be noted 

 in this way: An active branch of elodea or other pond 

 weed may be kept in a vessel of water in the dark until 

 it shows no starch with the iodine test. The branch is 

 then placed in spring water, which contains consider- 

 able air. On placing the experiment in sunlight, 

 bubbles of oxygen will immediately be given off. This 

 indicates that photosynthesis is active; and after a time 

 starch may be found in the leaves. g. ji_ Duogar. 



PHEAGMlTES (Greek, growing in hedges, which, 

 however, does not apply to this grass). GrumitiiHr. 

 Species 3, one in tropical Asia, one in South America, 

 and one, our species, cosmopolitan. Tall and stout per- 

 ennial reed grasses with long running rootstocks and 

 terminal panicles with aspect of Arundo. Spikelets 

 3-7-fld. Differs from Arundo chiefly in having the low- 

 est fls. staminate, the flowering glume sharp-pointed 

 but not bifid, and the hairs of the spikelet confined to 

 the rachilla. 



commtiiiis, Trin. Cojimon Reed. Culmusually 8-12ft. 

 high: Ivs. 2 in.wide. Marshes and along edges of ponds. 

 The ornamental feathery drooping panicles appear in 

 late summer or autumn. Gn. 31, p. 33. 



A. S. Hitchcock. 



PHRtMA (one .if the many names which Linnieus 

 never explaimal ). r, /7„»,ha./ . A Kmns of one species, 

 a hardy, p. rcimial In rh of lit lie ln.it icnlinral value. It 



siiiall I'ini': li or rose-Colored opposite fls. borne in 

 I ' :. iininal spikes. It seems to have been 



1 ' ' ' '• : laifope and is offered by one American 



ll.r:, in.. 1, auoiitlyingmeraberof the Verbena family, 

 and is by some authors made the sole example of "a 

 family of its own. This is because its ovary is 1-celled, 

 while the rest of the Verbenacese. as a rule, have a 2- 



.n\i.!nlc: radicle superior. 



Leptostachya, Linn. Lopseed. Height 2-3 ft.: Ivs. 



"i Ml. loll-, thin, the lower long-stalked: fls. at first 



' ' '"'II I ' :"i 111': ;iihI ill,- ,';(l\ X in fruit closed and 



' of the spike, the teeth 



I ' I i ' II).. June-Aug. Oom- 



■ " 1 ""I ■• » -. 1 amida to Minn., South 



PHKtNIUM (from Greek word for toad, because the 



hint inhal.its marshes). ScitaminAce(r!. About 20 herbs 

 f the Did World tropics with creeping rootstocks and 

 irge oblong showy radical leaves. The genus is closely 



