>rj B.wttTT. Cc uuueutt on L'/ufrmn \ y^ ^ 



also lias a ticueleus and a plate or granules of endoebrome, cither green or 

 yellowish-brown mi colon l' 



What appeal M the miaoscopi<l« most however are tlie siheiotis skeletons 

 which >ill ihc Valve* pontes. Thews skeletons are covered with various. 

 markings which di'lci according !u the species. The sculpturing on some i^ 

 vciy elaborate, while on others It consist* of punctate lines, some comparatively 

 course, white others such as Ampin pleura peihicuh, or Wiff&fiia jfwf/a/rtw.*, 

 have £-,000 to 114,000 lines- yer inch. As each littt has an average of oft 

 pimctae, it is utthe< dimcuM to realise how minute these markings art 



The va|v?s. although exceedingly ihin, are not solid but arc in Uvo layers, 

 usually with a supporting framework between them; the interior plate often 

 hat fine secondary markirupf. 



They reproduce themselves by vftriotcs modes of conjugation ami also by 

 division, the Utter method causing rihhon-Uke growths or chain- like series 

 in Which the diatom:, are attached hy one corner only. 



J. heir methods ol growths vary considerably; some ace tf&qhed to weeds 

 4ii* roclcs by etalks others grow on weeds in flusters, others are attached in 

 weed directly by the lower valve. One of the most peculiar ways in that of 

 Ihc DfiHTJi St-ltizoiH'Hia nad Pncwnnnn which gtow in tills interior r>\ the 

 fronib, nj <* small plant at tout \\ [ft high (named ttritllrworis riexan^p they 

 break in pieces at the slightest touch"). 



The group as a whole is divided into two subfamilies, the (Vwtntw, with 

 centrally built valves or arranged in relation to 3 central point, ami the 

 /VunufW, with markings arranged in relation to a median hoc. This hoe is 

 called the raphe, or psrudo-raphe, and che raphe proper is iu many species 

 a cleft communicating with the interior Of the valve. 



Perhaps the most curious phenomenon connected with the Dint own*: ma is 

 their jKwver o* movement. This occurs only with diatoms possessing a raphe, 

 and \l is considered that the moveitiutt is due to a cut cent set up in the 

 raphe, from one terminal nodule rn ihe centre nodule anrfl from this again to 

 the Olhtr terminal; this going on continually in both valves ol the fru slide 

 ;^rJ with the probable help of a Iouruc. tol the interior protoplasm, t'orccs -".he 

 Irustule in the opposite direction to the current, winch incidentally can he 

 revetted when necessary. 



The greater number of the .species are to he found only ;u ro5sil deposits 

 hi various parls of the world. On the Pacific coast of North America there 

 ate -numerous marine fossil beds, at Monterey. St. Monica. &t. Barbara, 

 \(oreno and many ullie* places In lli« easier it United. States I he re are 

 extensive deposits also in Maryland, and in Virginia where the city cl 

 Richmond i> built over a depntit ol unknown extent and averaging 2ft feet in 

 tl(j<.i;fies> Others dm lucatcd al Archangel and Simbirsk in Rmsia and 

 there are several in flune;arv, and all have Iheir peculiar forms, found only 

 iu their particular deposits. One of the best of these marine- deposits is located 

 at Oamani, N*ew Zealand, H belongs to the Oliuocene period and it surp;nsr.s 

 all others I think, m the hcanry and variety of |b« specter round ill il. 



TWO PUZZLING ALPINE HEATHS 



<LciK«pogoo hookcri Sond., o«id ListoMhe montona It. Br. 



v.WI<-Vi is fi,-.*v ffnn^t-Tfetl to rtie frirmf-r genu) I 



B> J. H. Wit.u*.. N.^tonal HerbaL'tum vi Vivtort^. 



LKfCOPOWN MO.NTANUS (K.Br > J. H. WiIUk amk noi- IL^.m^/A.- 



fnvnhno R Ri Pr&dr pftrfi Nov. fJoft : SAO (1*10) |. 



Tlie types of Luwntfa* HWlhWitt JtUii Ltiia.-j^ujnn bmbtft Sondec 



|Ajii*mt/i ?rt: J4H (lMSSH came from southern Tasmania ; but coinp^f^hk 



fiOpuUtious ol both eutitie? extend also to the mainland alps in Victoria and 



SF.. New South Wales. J. J> Hooker rctognt/irj both apecieN m Plfali 



