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SPECIES OF PLANTS. 



Sl'KKMACKTI-WHALE. 



834 



SPECIES OF PLANTS. All the individual forms of plant*, M 

 welt as animals that occur on the globe, may be collected into group* 

 lessmbling each other, and those groups are called species. A species 

 has been defined to be "a combination of individuals alike in all 

 their parts ;" " a systematic combination of homogeneous individuals;" 

 " a collection of individuals which will breed together and produce 

 fertile offspring." De Candolle say, a species is "a collection of nil 

 the individuals which resemble each other more than they resemble 

 anything else, which can by mutual fecundation produce fertile indi- 

 viduals ; and which reproduce themselves, by generation, in such a 

 manner that we may from analogy suppose them all sprung from 

 one single individual." However clear such a definition may be, it 

 would assist a botanist only in a very limited degree iu determining 

 whether a new plant should be looked upon as a new species. If 

 there were perfect structural identity between two individuals of the 

 same specie*, or if we could ascertain, on the physiological ground, 

 that the individual* after fecundation reproduced similar individuals, 

 it would then be a more easy task. But perfect structural identity 

 does not exist, and the physiological test cannot be always applied, 

 and hence the difficulty of determining what is really a species. 

 From this some have gone so far as to deny the existence of species 

 altogether, and assert that the supposed distinctions between plants 

 re altogether arbitrary and imaginary. This notion is however 

 altogether upset by the well-known fact of plauta maintaining for 

 centuries the some structural characters. 



However much it may bo regretted, on account of the vexatious 

 multiplication of species, that some fixed rules cannot be laid down 

 for their formation, it does not appear at present that anything more 

 than general rules can be given, and that much must depend on the 

 judgment and experience of the observer. 



As a general rule species are not distinguished by differences in the 

 Internal organisation, such differences being left for the higher divisions 

 into genera, orders, and classes ; but upon those superficial and 

 external differences which are independent of internal structure. Of 

 these may be named duration, dimension, surface, form, division, 

 numerical proportion, and colour. The value of each of these points 

 varies according to circumstances, and in proportion to the know- 

 ledge of the observer will be the skill with which he selects them for 

 distinguishing species. The duration of a plant is a point of great 

 importance, as in no instance do we find, unless from change of 

 climate, plants of the same species differing in being annual, biennial, 

 Ac. Dimension is rarely of any importance, and should only be taken 

 into consideration iu extreme cases. Differences of surface*, depending 

 on structural peculiarities, are of importance ; smoothness, roughness 

 from tubercles, and the existence of stinging hairs and prickles, are 

 points of value. The pretence or absence of lymphatic hairs on the 

 surface of 1> aves is a point that may mostly be disregarded ; they 

 are of more importance on other part*. The form of parts is only of 

 importance when it is the consequence of anatomical differences, that 

 is to say, the arrangement of the veins, &c. The division of organs 

 is not of much importance where it depends on the degree of the 

 laceration of the parenchyma. The union or non-union of contiguous 

 organs, as the parts of the calyx, corolla, tic., u of the greatest value, 

 being mostly uniform iu all the individuals of the same species. 

 The numerical proportion of the parts of a plant is of value iu pro- 

 portion to the small number of parts or organs; the greater the 

 number, the more subject it ii to variation. Differences in colour 

 are little to be relied on ; tho same may be said of odour and taste ; 

 u all these properties are liable to undergo change by a Blight 

 alteration of the circumstances of the plant. 



Those departures from identity of structure, which are considered 

 Insufficient to constitute a species, are called Varieties, and the points 

 of structure that should constitute a species or variety in frequently a 

 matter of difference, and it is no unfrequeut thing for one author to 

 reduce the species of another to mere varieties. Thus, Borrer has 

 made 71 species of Salur, but Koch has reduced them to 29, and 

 numerous examples could be cited. A careful attention to the 

 influence of climate, soil, elevation, tc., on species, would save much 

 trouble and vexation on this point. De Candollo has elegantly 

 summed up the iuflucnce of these agents on plants : " Let us sup- 

 pose," be rays, " what really happens, that the seeds of plants are 

 scattered at hazard over the surface of the earth ; or, to speak more 

 correctly, by causes that have no necessary connection with the exist- 

 ence of thorn plants ; such seeds will find themselves in an infinite 

 variety of situations : some which have fallen in soil that is -too 

 tenacious or too loose, too dry or too wet, too hot or too cold, do not 

 grow, and are soon destroyed. But between these extreme* come 

 will succeed, although it may be under very different circumstances. 

 Thu, for instance, if the place has not light enough, the plant will l>e 

 half blanched, which will be indicated by its palcuess and feebleness, 

 or by being pott' d, or by the diminution or even loss of iU hairs ; if 

 the light is too bright, the plant will be stronger, smaller, more deeply 

 coloured, bar ler, and more velvety than usual. Temperature also 

 exercise* tome influence, though in a lens degree ; in a cold climate 

 the Mune plant* are smaller and weaker than ordinary, the colour of 

 the flowers and fruit is paler, the wood worse ripened, their leaves 

 more deciduous, their fruit often abortive, and the sap destined to 

 nonrish it throwing itaelf into the neighbouring part*, sometimes 



changes their appearance. In a hot climate plant* become larger, 

 produce more wood, and their leaves have brighter colours and a 

 higher flavour. In the same climate humidity causes the appearance 

 of differences without end ; plauU that grow in water lose all their 

 hairs, their leave* become divided into capillary segment* so as to look 

 like hairy root*, their (terns and flower-stalks lengthen to reach the 

 surface of the water, and these different effects are further variable as 

 the water is still or agitated, clear or turbid, pure or mixed with 

 heterogeneous substances ; the varieties of Jlanunculus aqiiatilii offer 

 a remarkable example of this. If, on the other hand, a plant accus- 

 tomed to water is found to live in a drier soil, it become* covered with 

 haira, remains smaller than usual, and acquires greater hardness. In 

 air rarified like that of mountains, plants are generally found smaller 

 and more stunted than usual, while their flowers are larger than upon 

 the plain*. The influence of soil is not less manifest : if it is tena- 

 cious, the roots, which penetrate it with difficulty arc small, hard, 

 and clustered ; if it is very sandy, the roots become large, fleshy, and 

 fully formed ; if it contains a great quantity of carbon, the colours of 

 the flower are often altered, as those of the J/ydranyia into blue, and 

 of the Pink into violet ; if it is charged with salt, or if the plant is 

 within the reach of salt, even brought through the atmosphere, we 

 usually find the leaves more fleshy and more glaucous, as in Lotu* 

 comifulatut. All these different circumstances, combined with each 

 other in nature, are fertile causes of varieties, which arc still further 

 multiplied by cultivation." 



SPECTACLE-SNAKE. [XAIA.] 



SPECULA'KIA (so called from Sjieculum Venerit, Venus's Looking- 

 Glass, the old name of one of the species), a genus of Plant* belonging 

 to the natural order Campanttlacea;. It haa a rotate corolla, a linear- 

 oblong prismatical capsule opening by lateral pores between the caly- 

 ciue segments. In other respects thU genus resembles that of 

 Campanula, from which it has been separated by recent systematista. 

 The species are small annual plants inhabiting the regions of tho 

 Mediterranean and the temperate parts of Europe. One species, the 

 S. perfuliala, ii a native of North and South America. 



S. hybrida haa a simple or branched stem ; the leaves slightly 

 crenate, wavy, oblong, sessile, the lower leaves spathulate ; the calyx 

 scabrous; the segments lanceolate, longer than the corolla, shorter 

 than the ovary. This plant is a native of the corn-fields of Great 

 Britain, and is found commonly throughout the region of the Mediter- 

 ranean. There are several other species of this genus, all of which 

 are worth cultivating on account of their showy flowers. The seeds 

 should be sown in the open ground, where it is intended the plants 

 should remain. By sowing the seeds iu the autumn on early blossom- 

 ing may be ensured in the following summer, and by successive 

 sowings in the spring and summer they may be made to blossom for 

 several months during the summer. 



(Don, l>ichlainy<lcoui Plantt ; Bnbington, Manual of Brilith 

 Botany.) 



SPEEDWELL. [VKBOSICA.] 



M'KI/rKK. [/.INC.] 



Sl'K'KGULA, a genus of Plants belonging to the natural order 

 Caryophyllta. It U possessed of a 5-parted calyx, 5 undivided petals, 

 5 or 10 stamens, S styles, 8-celled 5-vulved many-seeded capsule. This 

 genus is found in fields and cultivated ground, especially on sandy 

 soils, all over the world. It is divided into two sections, one of which 

 possesses stipules ; the other is without these organs. On this ground 

 many writers have constituted new genera. 



>'. nii'etuif, Corn-Spurrey, or Yarr, has its leaves in whorls, with 

 minute membranaceous stipules at their base ; the stalk of the fruit 

 reflexed ; and the seeds hispid, with a narrow border. It is a native 

 of Europe, in gardens and fields, and iu North America on the banks 

 of the Columbia, and is common iu Great Britain. Though not culti- 

 vated iu England, this plant is of some importance on the continent, 

 and iu the Netherlands and Germany is sown for fodder. 



Three other species the S. nodoia, Knotted Spurrey ; S. taginoidci, 

 r\sarl-Wort Spurrey ; and 5. tubulaia, Awl-Shaped Spurrey are also 

 native* of Great Britain, but are neither ornamental nor useful. 



SPERMACETI, or Cetacaim, a fatty material obtained from the 

 J'hyictcr macrocephaliu. This animal, called the Cachalot, or Whiti- 

 Whole, is of immense size, frequently 00 or more feet in length, of 

 which the head constitutes one-third. This part U the chief reservoir 

 of the spermaci ti, which however is found in several other part* of 

 the body, mixed with the sperm oil. It is mostly lodged in two large 

 cavities of the upper jaw, one above and the other below, divided 

 from each other by the uoatrils. These cavities are subdivided into 

 numerous cells of unequal size, by ligameutous or tendinous partitions; 

 these partitions are of the same nature as those which separate the fat 

 in other animals, but, owing to the great size of the creature, of a 

 larger and stronger kind. The purest spermaceti is contained in the 

 largest and least ligamentous cells. The part in which it is lodged i* 

 quite distinct from the cranium containing the brain, which sperma- 

 ceti was at one time supposed to be. During the life of the animal 

 the spermaceti is in a fluid state, and on the head being opened hns 

 the appearance of an oily clear white liquid. On exposure to the air 

 the spermaceti concretes and deposits from the oil. They are HUM 

 separated, and put into different barrels. 



SPKKMACKTI.WIIAI.K. [CET.UKA.] 



