Grevillea

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part Semi- corticate i.

s. divaricata. Segments patent, osten divaricate ; apices stightly forcipate, laterat branches seW, for the most pari simple; internodes in the loWur part of the thallus almost naked, toWards the apices stightly corticaled. V f. borealis. Principat branches 450-650 in diameter belοW, laterat branches os stightly disserent diameter, beset With sub dichotomous or simple ramuli; internodos in tho loWer part of the thallus uitlier thinly corticaled or With a narroW barid, in theupper pari and the ramuli nearly naliud. Ait these forins With the exception os f. genuina are illustrated in the Plates, and they appear to bu lairly Woli marhed and easily

Primary silaments branched, creeping in the cellular membrane and muciferous canals of the Laminaria, secondary flamentSarising singly or in buutiles horn the primary sitamenis, erect, 6-7 μ in diameter, beloW occasionalty sparingly branched, above Simple orfurnished sparingly here and there With shori, divergent, secund

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The neW species appears to differ from E. stellaris in thebranched sporangia and ille rather more abruptly attenuated bases of the assimilation threads. According to tho author this species and E. 8tellaris bear plurilocular sporangia on the upper celis of thu assimilation threa is as Woli as at their bases. These sporangia are much lilio thoso bornu on the filuments of Leptonema, and Onthis account Herr Gran uould unito the tv o genera Alachista and Leptonema. W0 have Seon bodius similar to those deserit,ed by

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INDEX LICHENUM BRITANNICORUM.

115 L. herbidula, Nyl.

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INDEX LICHENUM BRITANNICORUM.

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INDEX LICHENUM BRITANNICORUM.

153 L. incompta, Dorr. f. minor, Stia. 154 L. subincompta, Nyl.η L. Oribata, Nyl.

h. Stirps, L. Permiserae.

n. Stirps, L. coeruleonigricanti8.

176 L. conglomerata, Ach. o. StirpS, L. aromaticoe. 177 L. squalida, Ach. 178 L. cinereo viren S, Schoer.

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INDEX LICHENUM BRITANNICORUM.

ment.

The a bove idea is in tho main in accord With the generallyreceived notion, that the rotation b0tW00n the gonidia and the lichen is one os mutualism or symbiosis. It is triae that SchWen- dener, Who si si propolin deii tho idea of tho dual nature of lichens, considered the gonidia af being suigod upon by the sungus, thus implying parasiti sui, but this vi0W has been corrected long ago, and

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61 MUSCINEAE.

PLANT DIS EA SES.

During recent years plant disesses appear to have ineruasea very considerably both in number and viruleiice ; Or, p08Sibly, What Was in early times attributed to atmospheric influence or Somesimilar vague Source has recently been traced to a Specific cause,

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llio attachs Os fungi, infestis, or bacteria. R0aliging the imp0rtanee of traeing the cause of disuase byexaet scientific methods, With the object os successsully combattingilio fame, State aid has been rendered in severat European conn- tries ; speciat laboratories have been constructed and placed under the charge of trained scientisic men, Whose entire time is devotedio the invo stigation os those dis eases most prevalent in their respective countrieS. Already the o utcome of this lino os actionlias rosultod in the publication os an enormous amount os information, the most successsul portiou of Whicli up to tho pres0nt doalswith tho cause rather than the cure. Yet this is What should bo: W0 cannot by any eXaci method cure a diSense, the cause of Which

The most eXtenSive reSearches, hoWever, in connection With this subject tiro carried 0n in the United States of America, Where,undor tho direction os the Depariment of Agriculture, numerouS laboratorios and eXperiment Station S are scattered throughout thocountry, the Work being carried on under the supervision os a con siderable number of Skilled specialisis ; and although there is ovidonee of eXternat preSSure OVer Whieli the author has no controlin the premature production Os SOme of the reporis, yet on thewholo the enormou S amount os Solid information contained in the

Introduction.

No plant diseases have attracted as Widespread attention as thorusis os cereales. For more than a hundred years scientisis and practical men ali over the World have made thesu parasites thesul det os study and thought, but a s yet nothing definito is knownas regards a practical and essicient means os preventing them. At

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ΡΙ ΑΝΤ DISTASES.

This paper, as the titie indicatos, Will deal With tho si si problem,