Pecbmber, 1901.] 



KNOWLEDGE. 



285 



together of the northern and soiUhern groups on tho 

 west coasts will not explain the presence of the Pyrenean 

 or American plants. Any suggestion of introduction — 

 early at-cideutal introduction, say, owing to trade with 

 Spain, or owing to seed borne across the Atlantic by 

 the Gulf Stream- will not for a moment be allowed by 

 botanists. These plants are native of the njitives. grow- 

 ius: abundantly in the wildest parts of the country, and 

 avoiding the haunts of man. Neither does it appear 

 possible* that they colonized Ireland by means of the 

 land-bridge to the eastward, whiih lia.s been spoken of. 

 for thev would have left some traces of their former 

 occupation of the wide areas over which they must have 

 passed. To account for the presence in the flora of 

 Ireland of the Spanish and IMcditerrancan elements, 

 we must look to a period far back in the history of 

 the island, when the continental edge extended further 

 westward than at present, and allowed migration to 

 proceed, from the Peninsula northward across the ex- 

 treme west of England into Ireland ; and for the 

 American plants, we must assume a former land-con- 

 nexion across the North Atlantic, probably by way of 

 Greenland and Iceland, joining the American with tho 

 Eurasian continent. At what period these lost lands 

 existed it is not. with our present knowledge, possible 

 to detennine, but the distribution of these plants, and 

 the discontinuity of their range, justify us in putting 

 it back to a time antecedent to the arrival of the bulk 

 of the vegetation as we now know it. and in looking 

 upon these species as some of the vei-y oldest components 

 of the British flora, the remnant of an army, the date 

 of whose invasion is lost, whose retreat has been long 

 since cut off, and who. reduced in numbers, have been 

 . allowed, by peculiar climatic conditions, to remain to 

 tell us of past times. 



To sum up. then, the flora of Ireland may be looked 

 on in a general way as a reduced English flora, just 

 as the English flora may be considered as a reduced 

 West Em-opean one ; in both cases the reduction is mainly 

 due to the breaking down of land-connections before tho 

 an-ival of the whole of the plants from the great 

 continental area to the eastward. The bidk of the 

 flora consists of these eastern plants, most of which have 

 colonized the entire island, though a few have not got 

 further than the eastern margin. Northern plants 

 arrived by way of Scotland, and spread widely, chiefly 

 down the western side. Lastly, in the west and south we 

 find traces of a veiy old flora which has migrated, 

 probably owing to fluctuations of climate, along the 

 former continental edge from the south-west of Europe, 

 and also over lands long since destroyed from the distant 

 shores of sub-arctic America. 



regular curricuhnii, and it has been said that every school will 

 be provided with ;it least one microscopo, so that tho senior 

 scholars may pursue thoir studies in a thorough manner. In 

 England encouraijoraont is bcins; given by tlie issue of Teacher's 

 Leaflets of " Nature Knowledge, " by tlic Agricultural Educa- 

 tion Committee. 



One of the main objects attempted to be achieved by these 

 leaflets is to load tho teacher to cultivate tho faculty of obsorya- 

 tion, to ti'.ace cause and elTect, and to become acrpiaintcd with 

 life-histories and ]irocessos of evolution and develo|Miient. If 

 students acquire tho habit of observation, they will quickly 

 learn to think, and an added interest will be imparted to their 

 studies by bringing them into actual touch with tho secrets 

 which the microscojje can alone reveal. 



It would seem almost a pity to give tho sc^holars a compound 

 microscope at too early a stage ; pages could be written on the 

 unnoticed structure wliich can be seen with a iiocket lens, and 

 it would be well that the work should bo graded, and that before 

 a compound raicroscoiio is used the worker shoidd have acquired 

 a facility with the pocket lens. 



There is no doubt that this now study will receive encourage- 

 ment, will be appreciated by the scholars and grow to largo 

 dimensions, and it will bo for English microscope makers to 

 anticipate the requirements by providing suitable instruments of 

 sound but plain construction, and at a sufTiciently moderate 

 price ; in fact, in a degree the success of the s(-heme so far as 

 microscopy is concerned depends on tho willingness of m.akera 

 to do their part. It is impossible to foretell the inflnonce\vhich 

 such teaching may have on the future of tho country scientifi- 

 cally, and it is not improbable that it will in time to come bring 

 an army of workers into tho ranks of microscopists, and serve 

 to re-create tho interest which it is considered by many is 

 dormant amongst amateurs at the present time. This is essen- 

 tially a British movement, and if Briti.sh makers Rup]>ly the 

 simple instrument, they will in due time bo requisitioned for 

 the more complete outfits which will bo necessary in conse- 

 quence of the desire for fuller knowledge and investigation 

 engendered by the elementary teaching. 



Focossixi: ATT,\cii5ri;NTS to Piioto-Micuo. (Jamkras. — 

 Many ideas have been formulated for making an effective 

 connection between the microscope fine adjustment and the long 

 rod which actuates it from the end of the photo-micrographic 

 camera. These have consisted principally of an endless band 

 passing round the milled head of tho microscope and a similar 

 head att.ached to the rod of the camera ; or a friction gear, in 

 which a wheel shod with inilia-rubber is arranged to engage with 

 the microscope milled head ; or a cord carried over the micro- 

 scope milled head and over pulley wheels on either side of the 

 base board having weights at the two ends, practically another 

 form of friction movement. In practice the endless band has 

 been the favourite, but it has possessed one drawback— it cannot 

 bo readily detached from the microscope. This difficulty was 

 overcome by the cord with weighted ends. A very neat and 

 simple fitting has been contrived by Mr. K. B. Stringer, winch 



Conducted by M. I.Cep§s. 



Microscopes ix Schools.— During the last few months, the 

 development of the .system of " Nature teaching " in elementary 

 schools has led to enquiry as to the most serviceable form of 

 microscope for farther developing the subject. In Scottish 

 schools in particular, this work is to become a part of the 



overcomes the obstacle with the endless band. The usual milled 

 head of the camera roil, .around which the co>-d is passed, is 

 mounted on a frame the lower portion of which fits into a sleeve, 

 permitting of the rod on whic^h the milled head is carried being 

 tilted forward when the band is to encircle the line adjustment 

 milled head, or to be removed ; the band is then made taut by 

 sotting the fitting vertical again, a clamping screw being 

 provided for securing it. In this position tho long camera rod 



