1 1 NATION. 



GEHVILLIA. 



10(11 



itumtion sufficiently warm, and with access to *ir, (be following 

 phenomena, according to the researches of l)e SausKiire, anil tlio 

 more recent ones of Bouatiugault, take place : 1 , absorption of oxygen 

 from the atmosphere ; 2, a disengagement of carbonic aciil 

 disengagement of nmmonia; 4, convenion of starch into dextrin, 

 gum, sugar, Ac. ; 5, increase in bulk growth of the embryo. 



All these phenomena were supposed to be connected with the 

 growth of the embryo, and the absorption of oxygen and the disen- 

 gagement of carbonic acid gas wen) regarded as on act of life and as 

 necessary to the process of germination. From this point of view 

 germination and vegetation, the growth of the plant, were stated to 

 bo antagonising processes* ; the one being a respiratory, an oxidating 

 process; the other a decomposing, a deoxidating process. At tlio 

 same time the albumen of the seed wan regarded as the sole source of 

 nutriment for tlio growing tissues of the young plant. In a paper v 

 read at the meeting of the British Association, July, 1845, 1 >r. Lan- 

 kester proposed a new theory of the phenomena of germination. It 

 is obvious that the only essential process of germination is the growth 

 of the young plant or embryo. The process of development of the 

 embryo from primitive cytoblasts, is precisely the same as that of c\. ry 

 oilier part of the plant, and from an identity of structure Dr. Lnnkester 

 infcricd there mutt be on identity of function. But the ordinary 

 theory of germination given a different function to the tissues of the 

 embryo from that of the other parts of the plant. This Dr. Laukestcr 

 considers unnecessary, and attributes the absorption of oxygen, and 

 the disengagement of the carbonic acid gas and ammonia, to the 

 result of the decomposition of the starch and protein coutninei] in 

 the perispcrm of the seed, whilst the growing cells of the embryo 

 appropriate the carbonic acid and ammonia with water, just in the 

 Fame way as all other cells in the vegetable kingdom. The facts by 

 which this theory is supported, and which are not explained by the 

 old theory are, as follows : 



1. In many plants there is little or no perisperm or albumen 

 developed, and .the conditions required for germination are those of 

 vegetation. 



2. Many plants with horny and hardened perisperms, as the Pliyt- 

 elepkat nacroearpa, the Pkaui.r tlaclylifera, nud species of llach-ii, 

 Cocot, and Atiroearyum, germinate, without consuming any appreciable 

 quantity of the perispenn. 



3. The quantity of carbonic acid obtained by De Saussure varied 

 not according to the number, but according to the mass of the 

 seeds, proving that it arose from the decomposition of the starch 

 as a chemical process, and not from 'the growth of the embryo as a 

 process of life. 



4. I >c Saiiasnre found that the relation between the oxygen con- 

 sumed and the carbonic acid gas given out was different in different 

 plants, but this relation ought to be constant if the theory of oxidation 

 or combustion during germination be correct. 



5. Boussingault observed that the changes supposed to be peculiar 

 to germination went on in the perisperm after the young plant had 

 d. v. loped its radicle and plumule, and was capable of an independent 

 existence. 



6. The changes which take place in the chemical composition of 

 the jx-rispcrm of the seed during germination con be artificially pro- 



: by mixing starch and protein (diastase) together, and exposing 

 them to the action of the atmosphere. 



This theory modifies the view which is mostly taken of the usepf 

 the albumen. It does not appear to be deposited entirely for the nSc 

 of the young plant, but in many cases is merely an organ of support, 

 and bears the same relation to the embryo that the wood of a branch 

 doe* to the buds which grow upon it. 



The progress of development in the embryo is usually first for the 

 radicle to lengthen, then for the cotyledons to unfold, and then for 

 the plumule to extend into a stem (Jiff. 8) ; but in Kudogenn, the plu- 

 mule of which is often inclosed in the very substance of the cotyledon, 

 a somewhat different process take* place. 



In 1'utmnogtlim lucent (fy. 4) the radicle generally swells and 

 lengthens, and at last produces from within its apex a papilla which 

 becomes the root; the cotyledon, which is spiral, at the same time 

 h ngthcns, and at last the plumule pierces through one side of the 

 embryo. In C'anma fadita (fiij. 7) the cotyledon always remains 

 inclosed in the albumen, merely swelling; the radiclo and cauliciiluit 

 ore protruded from the seeds; the former turns downward* and 

 emits a number of fine roots, the latter produces from within its 

 substance a conical body, consisting of several sheaths one wit Inn the 

 . which arc the rudiments of leaven. The (,'ocoa-nut differs from 

 i chiefly in its cotyledon swelling exci-niiii:-]-. ami becoming 

 spongy, filling the whole cavity of the m-e.l. ami absorbing the milky 

 fluid. Grasses offer only a slight modification of tin- same firm. 

 The embryo of maize, when divided vertically O'y. '.') appears like a 

 fleshy plate lying on one side of the flowery albumen ; at its back 

 next the albumen is the cotyledon, next the skin is a cone of sheaths 

 (as in C'rmna) forming the plumule, and at the base of the plumule 

 Another cone constituting the radicle. When such an embryo germi- 

 nates, the ra.licular cone pierces the soil, emitting from its interior, 

 through a kind of hheath, a few Blender roots, and protruding ''lnr; 

 from its surface; and th other cone, representing the plumule, 

 at the same time lengthens upwards in the form of a green 



spire, leaving the original external part of the sheath at its 

 baie (fig. 3). 



Many anomalies in the development of the embryo of both Exogcns 

 and Endogens might be pointed out, but they are of little interest to 

 any but professional botanists. Among the most striking ore the 

 following: In the genus I'intu the cotyledons are numerous, and 

 placed in a whorl (>/. 6) ; in the Cyrlnvxu the cauliculus enlarges 

 into a roundish turnip-like mass, from the apex of which *prii 

 leaves nml flowers, and from the base the roots (.>/. 1) ; i: 

 a parasitical plant (>./. til. the radicle becomes a flat plate, com. 

 the under . ido, l.y winch it adheres to the bark of the plant it 

 upon, and from which the singular roots proceed, which eventually 

 insinuate themselves through the bnrk between the pi:'' 

 wood. 



The manner in which the radicle protrudes itself is different iu 

 Exogens and Endogens. In the former its point gradually length. n 

 and becomes a new root ; this is called 'cxorhizal' germination: in 

 the latter the point of the radicle opens and allows the tn; 

 to escape from within it, a phenomenon to which the term 'eiuloihi/ud' 

 is applied. 



Attempts have been made to expedite the process of germination 

 by steeping seeds in a weak solution of chlorine, but no practical 

 advantage has been derived from the experiment. A more effectual 

 plan has been found for hard -shelled seeds, such as those of the 

 Acaeia, namely, boiling the seeds for a period between one and five 

 minutes. This has certainly, in some cases, had the effect of causing 

 seeds to grow which under ordinary circumstances would n.r 

 grown ; a circumstance to be ascribed, we conceive, to the hard 

 integuments of the seed being so much softened as to offer no great 

 resistance to the attempts of the embryo to escape from within them, 

 attempts which required no assistance when the embryo was in full 

 activity and the seed-coat comparatively soft, but indispensable when 

 these conditions are reversed by the loss of vigour in the embryo and 

 the excessive induration of the case containing it. 



OKHV1LLIA, a genus of Molluscous Animals belonging to the 

 Conchifera, or Bivalves, hitherto only found iu a fossil state. II. 

 Defrance first noticed the genus, which h r M. de Gerville, 



who discovered iu the Baculite Limestone of Normandy the specie* 

 on which the genus wa d. H. Dcslonchampg (' Mi'moires 



de la Societc Linccnno de Calvados,' 1824) proposed several modi- 

 fications of the character, so as to allow the genus to embrace four 

 otli.-r shells in addition to the first-described species, 6' 

 tolcnoitlci, viz.: OerriUuc pernoitlei (Perna arli-iilniilm, Sow., 'II in. 

 Con./ t. 66), . V i7/f/i(rt, iitoitotif and cottatutu, Vhich are figur- 

 cd in the memoir. M. Defrauce thought that the l.ivah 

 furnished with a hymns, but M. Dcslonchamps conceives that (ii-i-rillin 

 has no opening for the passage of that appendage. "Should this 

 prove to be the case," writes the reviewer of the memoir (/.>..] 

 Jouin.,' vol. i.), " whic^t we ore rather inclined to doubt, it will 

 effectually separate the shells of this from those of the other 

 of the Mulli IK; tr. Their nearest affinity is with those of / 

 which they may be at once distinguished by possessing an apjurcntly 

 inner additional hin^e, formed of several oblique teeth, variously 

 disposed, according' to the species." Mr. O. B. bowerby (Micnera of 

 Kcccnt and !'..- il Slu-ll-.') who judges the genus to hav< 

 marine from its as ! w 1. o states that there is good i 



for presuming that it was adherent by a hyasus, gives tins 

 following: 



It has the following characters: Shell oblong, nearly c.|iiivalve, 

 very inequilateral, and oblique; hinge-line rather lonir, lim 'ar. m '.-u-ly 

 straight, with many irregular rather transverse little pits, and 

 'clow the dorsal 



Mr. Sowi-rl.y regards it as an intermediate genus between A< 

 and /'mm. It r. IM observes, the former in its general 



form and external appearance; whilst its hinge is somewhat like 

 that of the latter, though suflieiently d H'Tent to enable us to point 



