The response to the action of light in diatropic leaves is, according to Haberlandt, due to the presence of epidermal cells which are shaped like a lens, or with lens-shaped thickenings of the cuticle, through which convergence of the light rays takes place and causes a differential illumination of the lining layer of protoplasm on the basal walls of the epidermal cells, by which the stimulus resulting in the orientation of the leaf is brought about.
Convergence of the light to a bright spot on the basal walls of the epidermal cells of Saxifraga hirsutum and fig.
Parker.) gnathism has been produced in half a dozen ways, implying numerous cases of convergence without any nearer relationship than that they are all derived from some schizognathous group or other.
Very important are also the investigations which show how, for instance in such fundamentally different groups as petrels and gulls, similar bionomic conditions have produced step by step a marvellously close convergence, not only in general appearance, but even in many details of structure.
It may here be remembered that of the mammalia man and monkeys alone are capable of convergence, and have a circumscribed macular area.
Owing to its position at the convergence of the Asiatic roads to the new capital, Nicomedia retained its importance even after the foundation of Constantinople and its own capture by the Turks (1338).
- Modern views as to the classification and affinities of the Arachnida have been determined by the demonstration that Limulus and the extinct Eurypterines (Pterygotus, &c.) are Arachnida; that is to say, are identical in the structure and relation of so many important parts with Scorpio, whilst differing in those respects from other Arthropoda, that it is impossible to suppose that the identity is due to homoplasy or convergence, and the conclusion must be accepted that the resemblances arise from close genetic relationship. The view that Limulus, the king-crab, is an Arachnid was maintained as long ago as 182 9 by Strauss-Diirckheim (1), on the ground of its possession of an internal cartilaginous sternum - also possessed by the Arachnida (see figs.
On the other hand, we must not rashly set down agreements as due to " homoplasy " or " convergence of development " if we find two or three or more concurrent agreements.
The determination of the relative degree of perfection of organization attained by two animals 1 A great deal of superfluous hypothesis has lately been put forward in the name of " the principle of convergence of characters " by a certain school of palaeontologists.
And the important consequences following from the demonstration of the identity in structure of Limulus and Scorpio are evaded by arbitrary and even phantastic invocations of a mysterious transcendental force which brings about " convergence " irrespective of heredity and selection.
One case of convergence of a sequence has already been considered in ï¿½ 58 (i.).
In most cases this is not possible; and we have first to consider the convergence of the sequence or of the series which it represents, and then to determine its limit by indirect methods.
This constitutes the general theory of convergence of series (see Series).
The sequence formed by taking successive sums of a series) which have to be considered in respect of their convergence or non-convergence.
For the algebraic theory of number, and the convergence of sequences and of series, see T.
Armies to cross the Austrian frontier and unite near Gitschin, a point conveniently situated about the convergence of the roads crossing the Bohemian mountains.
The convergence of the Prussian armies on the battlefield ended in the greatest confusion.
Again, to obviate the necessity for excessive convergence of the eyes so common in hypermetropia, the centre of the pupil should be placed outside the centre of the corrective convex lenses; these will then act as prisms with their bases inwards.
Considerable confusion arose from the convergence of these three brigades upon one village, and more than an hour passed before the troops could be disentangled and massed for further operations.
In other words, under the heading Sporozoa, as at present used, are included two entirely independent series of Protozoan parasites; the general resemblances which these exhibit are due to convergence brought about by their specialized mode of life.
In 1841 he published a valuable paper, "Sur la convergence de la serie de Taylor," in Crelle's Journal.
On the other hand, to produce convergence with water or hydrogen gas, in both which the velocity of sound exceeds its rate in air, the lens ought to be concave.
But it is submitted that their harmony and convergence give them some additional claim to acceptance, and at any rate do something to secure each one of them singly - the Nativity in 7-6 B.C., the Baptism in A.D.
The most fundamental distinction in analysis is that which must be made between homogeny, or true hereditary resemblance, and those multiple forms of adaptive resemblance which are variously known as cases of " analogy," " parallelism," " convergence " and " homoplasy."
The convergence of Roman roads at this point would make the place a particularly convenient centre.
An important phenomenon connected with insect mimicry is the convergence of several species in the same area towards a common type of coloration and shape, exhibited by one or more than one protected form.
Again, no single point in the cortex evokes the act of ocular convergence and fixation.
The pragmatic doctrine of truth, which it is now possible to outline, results from a convergence of the above lines of argument.
The phenomena of convergence are to some extent other instances of the same kind and supply evidence that organisms, so to say, fall into grooves, that their possibilities of change are defined and limited by their past history.
A reservoir, roofed by the convergence of its sides, which were of large regular blocks, was discovered in 1832, but filled in again.
Upon the convergence of the manifold lines of investigation rest all reconstructions, all methodical studies of biblical religion, law and prophecy, and all endeavours to place the various developments in an adequate historical framework.
For spectroscopic purposes the Cassegrain form has peculiar advantages, because in consequence of the less rapid convergence of the rays after reflection from the convex hyperboloidal mirror, the equivalent focus can be made very great in comparison with the length of the tube.
There must be convergence in a unitary principle, soul or consciousness, which is that which really functions in perception, the senses and their organs being merely its instruments.
The valley of the Po formed the main artery of trade between western Europe and the East, Milan being besides the point of convergence for all Alpine passes west of the Brenner (the St Gotthard, however, was not made accessible until early in the 13th century).
The reason for this convergence is that, whereas there is found great difficulty in characterizing the elusive nature of the sacred, its mode of manifesting itself is recognized to be much the same in all its phases.
For the convergence of the continued fraction of the second class there is no complete criterion.
The theory of the convergence of continued fractions is due to Oscar Schldmilch, P. F.
Van Vleck have written on the convergence of infinite continued fractions with complex elements.