II 



STOMATELLA. 



STONESFIELD SLATE. 



is 



Host ml plate rounded Bud nearly pointed in front 

 0. Seyllanu. Length about 4J inches. It is found in the Indian 

 Seas and on the couU of Mauritius. 



Cbroau ( LatreilleV This form does not appear to M. Milne- 

 Edwards to differ sufficiently from the fyuillir, properly no called, to 

 authorise its generic separation ; but as he had not observed it himself, 

 he continues to retain it as a genus. The following is Latreille's 

 character : Lateral and posterior appendage of the third joint of the 

 last six feet (the adactyloua and thoracic) in form of a membranous 

 blade or battledore (pallette), which is nearly orbicular and a little 

 bordered (rebordee). 



C. Scolopendra. (See Guerin, ' Iconographie,' pL 24, 6g. 2.) 

 STOMATE'LLA. [HALIOTIDJB.] 



STOHATE3 (from the Greek OT^UI, an 'opening,' or ' mouth '), in 

 Botany, are small longitudinal openings occurring in the epidermis of 

 plants, and usually bounded by two or more luuato or kidney-shaped 

 v -. |sj 



The first botanist who observed the existence of Stomates was Grew, 

 who, in his ' Anatomy of Plants,' published in London in 1682, gave 

 an imperfect representation of these organs, and stated that they 

 existed on several parts of plants, but he gave them no special name. 

 Malpighi afterwards described their existence in the epidermis of 

 Marckantiaetir, where they are very large, but entirely overlooked 

 them in the higher plants. Guettard was the next writer who noticed 

 them, and believing them to perform the office of glands, called them 

 'glandes miliaim' (glandulse miliares). Saussure also thought them 

 glandular bodies, and called them cortical glands. Hedwig and Glei- 

 chen were the first to give accurate drawings of them ; and from that 

 time their existence excited general attention, but they received a 

 variety of designations. Hedwig called them Spirocula and Pori 

 Exhalantes ; De Candolle, Pores Corticaux ; Krocker, Uimiu Annulate; 

 Mirbel, Pores Elongees. Sprengel and other German writers designate 

 them as SpalUifTnungen ; Rudolphi called them Pores of the Epidermis ; 

 Link proposed the name Stomata, which has since been adopted by 

 De Candolle, Brongniart, and Mirbel in France, and Lindley and 

 Henslow in England. Link has however since proposed the name of 

 Hautdriiscn (skin-glands), and this term is adopted by Meyen and 

 later German botanists. 



The structure of the Stomates is best seen in tho monocotyledonous 

 plants, in which they generally occur of a larger size. They are quite 

 imperceptible to the naked eye, but may be discovered by a lens of low 

 power. In general they will be found to consist of two kidney-shaped 

 bodies, which are merely cells of cellular tissue filled with a green 

 matter, and from this circumstance contrast with the transparent 

 cuticle in which they are placed. The kidney-shaped bodies lie with 

 their incurved edge* presented to each other, and their extremities 

 unite with each other so that they leave between them a little oval 

 chink or opening. This opening communicates with the parenchyma 

 of the leaf or other organ underneath the cuticle, and at this point 

 the cellular tissue U loose, and frequently a large cavity U observed, 

 into which the Stomate opens. Nees von Esenbeck, Brown, and others 

 denied at first that the space between the lunate bodies was an opening, 

 but the observation of later writers seems to have proved this point 

 (Lindley, ' Introd. Bot ,' p. 52.) This difference among observers may 

 perhaps be explained by the fact that the kidney-shaped bodies have 

 a power of contracting and dilating, and thus closing or opening tho 

 spaoe between them. This was first observed by Comparetti, and has 

 since been confirmed by other writers. 



The Stomates are not all composed of two cells ; those of Marchanlia, 

 according to Mirbel, are composed of four or five cells, which are 

 arranged circularly, forming an upper outer rim of the Stomate. Some- 

 times additional cells are found above these, but they differ little, 

 except in their arrangement, from the cells of the tissue by which 

 they are surrounded. This U one of the simplest forms of Stomate. 

 In jVeriw oleander the Stomates consist of cavities in the cuticle, 

 which are filled up with little hairs. Dr. Lindley has described in 

 Keptntktt two sorts of Stomates, " the oue oblong, semi transparent, 

 and almost colourless, with numerous pellucid globules in the cavity 

 of the c-lls ; the other roundish, much more opaque, and coloured 

 red." Although the form of the Stomates U most frequently elliptical, 

 they an sometimes quite spherical, as in Oitcidium aliiuimum, and 

 Link has noticed them of a quadrangular form in Yucca, yloriota. 



The Stomates are mostly arranged irregularly upon the surface of 

 the epidermis, occupying generally about equal distances from each 

 other. Then are however some remarkable exceptions. In the grasses, 

 for instance, and some other monocotyledonous plants, the Stomate* 

 an arranged in regular rows, which run parallel with the bundles of 

 woody tissue which enter into the composition of the leaf. In 1'hor- 

 miupB trnajc and in I'ixui the Stomates an also arranged in a longitu- 

 dinal series. In Begonia tpathndala the Stomates on the tinder surface 

 of tha leave* an collected together in the form of little rosettes. The 

 same is seen in Cratiula cordata and C'. arboretcau. 



Stomate* an found on plant* whenever then is a distinct epidermis, 

 and they exist on nearly all the part* of a plant exposed to the light. 

 In the lower cryptogamic plants, M mosses, Fungi, Lichens, and Algae, 

 they have never been found. Plant* growing in the dark do not posse** 

 them, nor are they present on root* or the ribs of leaves. They an 



found on the bark of herbs and trees, but in the latter only whilst 

 the bark is herbaceous. In those plant* which live under water, a* 

 the Zottera, Ceratopkyllum, and 1'otamoyelon, they an not found. 

 Those part* of the leaves of some plants which an concealed under 

 the ground, as in the onion, Ac., have no Stomate*. All the parasitical 

 plants which have not a green colour, as the Orobanchacea, Lathrta, 

 and Monotropa, are destitute of Stomates, whilxt those which an 

 green, as the Loranthui, have abundance. They an only rarely found 

 upon the filaments of the stamens, the anther*, or the style*. With 

 the exception of Canna, they have not been found on the seeds of plants, 

 nor are they present on fruit*, except such as are membranous. 



Stomates an not always present on both surfaces of the leave*. 

 They are however much more frequently absent on the upper than 

 on the under surface of the leaf. 



The number of stomates contained in a given surface varies very 

 much in different species and families of plants. Many observers 

 have occupied themselves in counting them, and the following table 

 gives the result of some of the observations of Spreugel, Krocker, 

 Thomson, and Liudley on this point : 



Brown is of opinion that the figure, number, and size of the Sto- 

 mates might often be made use of to indicate the affinities of genera 

 and natural families of plants, and ho* proved that this is the case in 

 Proteacetr. Schleiden has pointed out the relations and differences of 

 these organs in Cactacem, Conifera, Piperacece, and other orders. 



Many different views have been taken of the function of Stomates. 

 That they are organs by which the process of exhalation is carried 

 on as a vital process, there is much reason to suppose. They exist in 

 the greatest abundance in those parts of plants in which this opera- 

 tion is going on, they are also most abundant in membranous leaves, 

 which are known to exhale most, and are deficient in succulent leaves, 

 in which there is little exhalation. It was long ago observed by 

 Comparatti, that the mouths of the Stomates were open by day and 

 closed at night, and this is quite in accordance with what we know of 

 the action of light on the function of exhalation. It is more active 

 in the day, and the mouths of the Stomates are opened to allow of 

 the exit of the vapour. Another argument in favour of this view is 

 derived from the non-existence of Stomate* in those families of plants 

 in which no proper transpiration takes place. There is no doubt that 

 the surface of plants absorb moisture when atmospheric conditions 

 an favourable, and it is probable that under those circumstances the 

 Stomates become organs of absorption. 



(Meyen, Pjlamen PhytMogit; Lindley, Int. Hot.; De Candolle, 

 Vrganoyraphtt Yfgttale ; Brongniart, Ann. da Kc. Nat., 1834.) 



8TOMATIA. [HALIOTIDA] 



STO'MIAS, a genus of Fishes belonging to the family Kiocidce. 

 They are distinguished by the muzzle being very short, the mouth 

 very deeply cleft, the opercula reduced to small membranous laming) ; 

 the maxillaries fixed to the cheek ; the intermaxillary, palatine, and 

 maxillary bones are rather sparingly furnished with teeth, and these 

 are long and booked, and similar teeth are observable on the tongue. 

 The body U elongated, the ventral fins are placed very far back, and 

 tho dorsal fin is placed opposite tho anal fin, on the hinder extremity 

 of the body. 



Only two species of this genus are known, both of which are 

 inhabitant* of the Mediterranean. One, S. barbattu, has been so 

 called on account of its having a long barbule on the chin. Hoth 

 specie* are of a black colour, but have numerous rows of small silver 

 spot* on the abdomen. 



STONECHAT. [SAXICOLA.] 



STONECROP. [SEDUJL] 



STONESFIELD SLATE, a small band of rock separating the 

 Gnat Oolite from tho Inferior Oolite. The accumulation of organic 

 remains in this formation is one of the most remarkable phenomena 



