2C, THE WITITK PINE. 



anil iiro tlicrofore teniUMl tlie nutvv ccUh; tlio ntlirr UimI makes ii|i llii> intennoiliato mws anil arr known as the 

 innrr relit*. 



In the appearand! of l>oth ontcr anil innrr colls thorp is a marked ami ronstant ililVorcnco in ilitVorcnl groujiH 

 of pim's. Wliiln tlio intorior of tlio wall of tlio ontiT i-iills (tranHverse trachoiilK) Ih Hmootli in 8onio groups, it is 

 lirsi't witli niimrrons biilil pro.irctions in otIierM. Similarly tho inner rolls (parinrliyma) of tlio sjirini; woml of earli 

 rav ill Homo f;ii)nps liavr lint a Hin;;Io largi' pit riiiniiiiiiiiralin;; willi tin' iioi;;lilmriii;; traclioiil, wliilr in other (groups 

 this is hroii);lit alioiit liy tliri'O to six sinaller pits. 



j'.asi'cl n|ion these ilitroroiires, the followin;; classilicatioii nf the wiioil i>l' ilitlrrent speries i>t pines is jirojioseil 

 liy lir. .1. Si liriieiler: ' 



Section 1. Walls i»r tho trai^hoiila of tin- iiitli ray with dcntatn i>riijoriii>iis. 



o. Ono to two large, simpli' jiitJi loearh trarhi'iil on llir railial walls of thr nils of tlii' iiilli rav. -1 1 roup I. lUiprKscntnil in lliis loniilr)- 



only by /•. ri>«inojia. 

 ((. Thrw to aix niniplo pita to I'nch tiaihciil. on llii' w.ills of Hii^ rills of Ihr pilli ray.— I imup 2. I', taivla. paluKtriii. iti' . itirliiiliii); 

 most of our "haril" anil "yollow" pinrs. 

 Skitids II. Walla of tracliuiila of pith ray Hiiiootli, without ilintatr pniiiiclions. 



a. Ono or two lar;;i' pits to rai-li trachciil on tho rnilial walls of oach roll of tho pith ray.— Croiiji :t. I', ntruhut. tamhfrtiaua, anil othor 



triio Whit* IMnoa. 



b. Throe to six small i»its on tho radial walls of oaoh coll of tho pith ray.--(;rou]i 4. /'. ^larritaiui, anil othor nut piuos, Incluilin^ also 



V. halfovrinna. 



Retnrniiif; to the nimltillary ray of the White I'iiie, it is ohscrveil that tlie walls of the outer rells an- thin 

 (l.ri // to 2 ;0 ; the round jiits ipiiti' varialile in niiiuliir and size, liiit always as small, and often smaller, than the 

 pits of the traiheids in tlie summer wiioil; also that the walls of the inner v.vWs are thin (1..") /< to 3 //), for the most 

 part very thin, liein;;; largely occnpieil liy pits; that the jiits are large ovals on the r.adial walls of the cells in the 

 spring wood, small ereit ovals in the summer wood, and small .'iiiil irregular in outline almve and liolow where tho 

 inner cells iiimmunicalc with each other. The length of these cells varies, even in tho same ray, liitween .'lO /< and 

 300 // ; tho width was foiind to he aliout 7 n for the outer ami 12 // for the inner cells; tho height, more varialile in 

 the outer than in tho inner cells, and less variable than either widtli or length, may lie set at about 23 // for outer 

 and inner cells. Tho average number of cell rows in one medullary ray, for the specimens studied, is 7.5, whereof 

 2.r> fall to the outer colls and 1.9 to the inner colls. The limits of the total nnnihcr of cell rows weio 2 and 16; the 

 height of the ray, therefore, 40 // to 3G8 //, dimensions scarcely appreciable to tho unaided eye. What is lost in si/.o 

 is gaineil ill iiumher; on an average 21.3 medullary r.ays were counted mi 1 S(|iiaii' millimeter, or 13,:H2 to 1 si|iiaie 

 inch of tangential section. 



A study of the wodiI in its physical and iii('i;hanic;il jiroperties, by Mr. I''ilii)i'rt Uiitli, will 1»', 

 foil 11(1 fiirrlicr on in this mono{rrni)li. 



KXPI.ANATKIX OI' IM.ATK VII. 



1. Transverse section of fresh shoot, cut in summer of first year X 25. The /one of small cells siinouiuling the ]>ith 



includes the wood and inner bark, both of which are traversed radi.ally by tho niedull.iry rays. The thick 



cortical paromhyma outside of these is marked by the presence of a number of largo resin ducts. 

 5. Portion of i]iiileriiiis, with ajipeiulages. I'.ene.ath the epidermis a few cells of the cortical )iarenehyina eiinl:iiiiing 



starch. 

 S. Highly in.agnified view of a p.irt of tlie transverse section, showing the .structure of woml ami iiimr li.irU. with the 



thill-walled cells coiii]iiising the eambinm lying between them. 



[I'igs. 2 and 3 were drawn with great lare with the eainera, but iinfortiiiiately no statement of I he magiiiliiatiim 

 w.as preserved with them.] 



KXPLANATION OF I'l.ATK VIII. 



/. dross Hoction of wood x n."). The section includes parts of throe medullary rays, the middle one of w hiili is cut 

 partly tliningh the inner colls and partly thrnngh tho cross tr.acheids. The gradual transition from spring to 

 summer wood is clearly shown. Part of a resin ilmt is seen on the right. 



2. Radial loiigituilinal secliou of wood X 21)0, showing a (evr of the thick-walloil tiaclnids of the summer woml 



followed by the large thin-walled ones of llio succeeding spring, both crossed by a medullary ray. The 



liordered ]iits of tlio outer cells of the ray, shown both in section and surface view, are in strong luiitrast with 



tho simple jiits of tho inner cells. 

 .1. Tangential section of wood X 200. 

 ■I. Cross section of jiart of twig colleiteil May 20, l!<8(i, X 17.'i, showing lamliinm and development of woinl and b.irk. 



The woody ring is about oiio-third its final thickness. 



GROWTH AND DEVELOPMENT. 



The seeds of tin; VVhitc I'inc retain tlieir vitality i'or a loiij; prrioil. Triistwdrtliy observers 

 state thiit a fair percentage will grow after being kept live years or more. Tlio conditions of 

 germination and sncceasful growth are, in general, the saino as for oilier pines, namely, a suitable 



'l>r. .1. .Schroeder, lias llol/ ilir Conifcreii, 1.S72. 



