NOVEMHER 24, 1898] 



NATURH 



91 



the exposure to direct sunlight. I'ossilily the tcmperalure had 

 some effect." It is further In lie noted thai in every case of 

 induced apoRamy " normal embryos were produced when con- 

 ditions |)ermittcd fertihsation." Now the conditions of pre- 

 vention of ferlihsalion, exposure to lij;hl, and possibly also a 

 high lemperalure, all lead to a plethoric slate, which we may 

 thus recnjjnise as a precursor of mduced apogamy, possibly also 

 of apoyaniy at lar^e. 



On Ihe other hand, the circumslances which piecede or 



accompany aposjjory are commonly those of deficient nutrition. 



In the case of U(;o Brizi's /'iiiiaii'a, it is mentioned that the 



ca|>sules were atrophied and buried in Ihe .soil, where ihey 



could not obtain nourishment by Ibeir own assimilalion. In 



the induced apospory of .Slahl and I'ringsheim the i;rowllis 



appear upon parts of Ihe chopped up seta, isolated from their 



' usual sources of supply. Amonj; Ferns, the conditions ot 



' nutrition which prece<le apospory have not been noted in all 



' cases ; but the following facts are interesting. Athyritiiii /•'ili.x- 



\ foemina var. rlnrisu'iiia is a pale chlorolic I'ern with exiguous 



■ leafage, while the more or less complete arrest of ihe sporangia 

 Is a concomitant of apospory. In /'olyslUltuni an);iilnic var. 

 pukhtrrimiim there is no obvious disturbance of the vegetative 

 organs, bul I have specially noted the sporal arrest, which, in 

 the specimens examined by me, appeared to be complete. This 



■ is, then, a concomitant of apospory, though it may be uncertain 

 ' how far there is a casual conned ion. In the case of apospory 

 I in I'lifis ai/iiiliiia, reporte<l by I'arlow, there is an irregular 

 ' diminution of leaf-area in the pinnules which show apospory ; 

 ' this is accompanied by various stages of abortion of the 



sporangia, though some fully-matured spores were found. 



' Mere, as also in /'olyslie/uim nii,t;iila>e, the tips are specially 



(affected. I'arlow remarks, "Ihe sporangia became more and 



\ more irregular the nearer they were to the tip." In the case of 



I Sco'.opciidiinm vul,i;are, the plants which showed apospory al 



1 so peculiarly early a stage had been raised by Mr. Lowe from 



J prothalli which had been repeatedly divided, a process calculated 



' to affect the physiological condllion. The aposporous plants of 



' Tridiomaiies alalum, pyxiilijciiini, and A'aiil/iissii, were all 



' cultivated under artificial condiiions, and are characteristically 



] shade-loving plants, a habit which must affect their nutrition. 



1 Perhaps the most interesting case, however, is that described 



: by Atkinson in Onoctea. In plants from which, by removal of 



the foliage leaves, the sporophylls had been induced to change 



' their character and develop as foliage leaves, the sori were 



I arrested. " When Ihe leaf has lost so much of its reproductive 



I function that Ihe sporangia are becoming rare or ruilimenlary 



in the sorus, apospory freipiently occurs, and Ihe placenta 



develops among the rudimentary sporangia prothalloid growths." 



Mere is, again, a case of deficiint nutrition; the assimilating 



j leaves, after formation, but before they could have carried their 



I functions far, were removed. The plant makes an effort to 



I supply iheir place at the expense of spore-production ; arresl of 



sori and sporangia is the result, accompanied by cases of the 



direct vegetative Iransilicm to the prothallus. From these 



I examples we see that deficient, or, al least, disturbed nutrition 



IS freipienlly, perhaps always, a concomitant of apospory. Thus 



there is some countenance for the view that apospory and 



apogainy follow on converse con<litions of nutrition. 



We may next inquire how these converse condiiions may lead 

 to Ihe changes in question ; and esj)ecially the slate of the 

 nuclei ought lo be considered. Owing to practical difiicullies 

 of observation the behaviour of the nuclei in apogamy and 

 apospory has not been directly followed. Hut if the nuclear 

 diflerence between the two generations be as it is believe<l, 

 nuclear ehangcs will be closely connected wilh lhe.se vegetative 

 transiii,m.s. What could appear more natural than that 

 apogamy, which presumably involves a doubling of the chromo- 

 somes, should follow a conditi.m of plethora, and that apospory 

 which presumably involves a halving of the chromosomes, 

 should follow deficient nutrition ? 



One further fact in either case appears lo me lo be s[>ecially 

 noteworiliy, that the changes are not confined lo a single cell. 

 The directly apogamous bud of Neplirodium Filix mas may per- 

 haps be referable lo a single cell, but Dr. Lang shows by 

 nunierous examples that the transition from characteristic li.ssue 

 ol the gamelophyle lo that of ihe sporophyte may arise al various 

 points and involve considerable Iracls of li.ssue. Similarly I 

 have shown in the case of apospory that the change may affect 

 not one cell only, bul cell-groups at various and distinct points 



NO. I517, VOL. 59] 



on the .same individual. It would seem that there is a wide- 

 spread disposition of the tissues to undergo the change. 



I'Vir my own part, I think Ihe usual attitude on the chromo- 

 .some cjueslion has been loo absolute and arithmetical. Evidence 

 is accumulating from various sources that the usual numbers are 

 not sirielly maintained ; it is known that in vegetative cells 

 there arc often considerable differences of Ihc number of 

 chromosomes from those in the sexual cells of the same ])lant, 

 while observers have noted the irregularities in Ihc divisions of 

 the pollenmolhcr-cells in such plants as llemerocallis and 

 'I'railescaiilia. If there be any causal connection between the 

 number of chromosomes and the morphological character of the 

 sporo|)hyte and gamelophyle, irregularities such as these al least 

 countenance the idea of nuclear inslabilily being possible ; it 

 will be a question for ispccial Ireatmenl and inveKligation how 

 far nuclear instability is connected with disturbecf nutrition. 

 Hut inio Ihe mechanism of the jiresumable nuclear change, and 

 the (pieslion whether it be sudden or gradual, we cannol enter 

 with any more than a speculative interest, in the absence of 

 tlirect observations. Whatever Ihe nuclear details may be, I 

 regard it as a mailer of very great importance to recognise that 

 special condititms of nutrition commonly accompany, if indeed 

 lliey do not actually determine, those changes which we term 

 apospory and .apogamy. Hut Ihe story of the past is not simply 

 a matter of conditions of nulrilion, as we see them now in- 

 lluencing Archcgoniate plants in iheir present highly specialise<l 

 slate. The real question is a purely historical one, Mow ilid 

 Ihe present slate of things come about ? 

 ( To be continued.) 



THE TEACHING .OF SCIENCE IN 

 ELEMENTARY SCHOOLS} 



\/(JUR Cominitlee are able to report that the quantity, if not 

 the quality, of the leaching of science subjects in 

 elementary schools has made progress during the past year. 

 The following table, made up from the return issued by the 

 Education IJeparlmcnl, gives the figures for the scientific class 

 subjects as com|)are<l wilh Isnglish. In Ihe re|)ort for last year 

 il was mentioned that the number of school departments taking 

 object lessons would greatly increase, as the Ciovernmenl code 

 of regulations announced that ihey would become obligatory 

 in the three lower standards on and after September I, 1S96. 

 We now .see the result, so far as the schools arc concerned 

 whose .school year ended between August 31, 1896, and 

 August 31, 1897, but the lull effect cannol appear until the 

 next year's return, the whole of which will be in ihc obligatory 

 period. 



Ueparlmcnl. j»890-9t 1891-92 1892-93 1893-94 1894-95 1895-96 1896-97 



K'lgHHli 19,815 



(Ji-oRraphy ... ... 12,806 



Klcmvnt.iry Science 173 

 Oljjcci Lc»son» ... — 



■8,175 

 ■3,485 



The number of deparlments in " schools for older scholars" 

 for the year 1896-97 was 23,080, all bul 10 of which look one 

 or more class subjects. Hut history was taken in 5133 depart- 

 ments, and needlework (as a class subject for girls) in 7397 

 deparlmcnls, and sundry minor subjects in 1056, making, with 

 Ihe other four subjects of ibe table, a total of 55,456. This 

 shows an average of more than 7.\ class subjects to each depart- 

 ment ; but it must be borne in mind that the same subject is 

 not always taken in all the standards, in which case three class 

 subjects will appear in the return. 



Il was remarked in the last report that "the increased 

 leaching of scientific specific .subjects in the higher standards is 

 llie natural consequence of the greater attention jiaid to natural 

 science in the lower pari of the schools." The following table 

 shows the correctness of this inference : — 



I Kcportof theCommillcc cotiMHlingof Dr. J. H. Gl.idv 

 of. It. K. Armstrong (Secretary), I'rof, W K, ' 



(Chftirman), 

 Air. (jeorge 



l.n.l'.lonc. Sir John Lubbock, Sir Philip MaKiiui, Sir II V. KoKoe, and 

 >r. -S. V. 'I'hoinpson. (Kcad before Section U of the Hrilish Aiisocialion at 

 Hriilol Meeting. 



