Cylindrical Mass Research Articles

The Cyprus Processionary Caterpillar (Thaumetopoea wilkinsoni, Tams)

Thaumetopoea wilkinsoni, Tams, is known only in Cyprus, where it abounds, attacking all species of pine, but chiefly Pinus halepensis, Mill.In the plains the adults emerge from the end of August to the beginning of October. The eggs are laid, shortly after emergence, in cylindrical masses round pine needles, the masses averaging 150 eggs. Only one mass is laid by each female. The incubation period is about 45 days.The five larval instars are described, as well as the differences in the habits and nests in the various instars. The length of the larval life varies from 116 to 173 days. Only in the fourth do larvae remain in the same nest throughout the instar, as they frequently migrate, moving in single file to new feeding grounds, and there construct a new nest. Six such migrations have been observed for one colony during its three earlier instars.Pupation, which commences in the plains about the middle of March, takes place in the ground in silken cocoons at a depth of ¼ to 3 inches, the pupal life lasting all through the hot weather.Altitude considerably influences the life-history—the greater the altitude the earlier the emergence of the adult and the later the pupation of the fully-grown larvae, with consequent alterations in the length of the larval periods.Of the checks, two species of Chalcid egg-parasites have been shown to occasion a parasitism of over 17 per cent., and three species of Tachinid larval parasites sometimes to occasion a parasitism of at least 30 per cent. There is also an Ichneumonid larval parasite. This latter aestivates in the pupa of its host ; the Tachinids leave their larval hosts and pupate in the nest of the processionary.Re-afforestation in Cyprus, both natural and artificial, being an urgent necessity, this processionary is of great economic importance, as stands of young trees suffer very heavily from its attacks, one colony of larvae being sufficient to strip and, if the late rains fail, to kill a small tree. The writer considers, however, that control is possible by encouraging the parasites and predators, methods for which are outlined.

The Reaction of a Stream of Viscous Fluid on a Rotating Cylinder.

In “Die Naturwissenschaften,” 6th February, 1925, p. 93, there appears an article by Prandtl entitled “ Magnuseffekt und Windkraftschiff,” giving the following explanation of the phenomena under consideration.In a stream of viscous fluid a non-rotating cylinder builds up an accumulation of retarded fluid with considerable vorticity (Fig. 5). This fluid reaches the neighbourhood of the near dead water point with a loss of kinetic energy and velocity by dissipation. At the somewhat indeterminate boundary of the boundary layer it is in contact with fluid which has lost its kinetic energy and velocity in acquiring an increase of pressure approaching the dead water pressure. The retarded fluid is pushed away from the dead water point by the higher pressure fluid (Figs. 6, 7), and ultimately it breaks up into cylindrical masses which are detached and carried away by the stream (Fig. 8).

The Ciliary Mechanisms on the Gill and the Mode of Feeding in Amphioxus, Ascidians, and Solenomya togata

The mode of feeding in Amphioxus is effected by– (1) The maintenance of a stream of water through the pharynx by rows of lateral cilia on the gill-bars. (2) The throwing out of mucus from the endostyle on to the gill-bars to serve for entrapping food-particles. (3) The collection of food-particles by rows of cilia on the pharyngeal surface of the gill-bars; these cilia woraSkip the foodparticles with mucus into cylindrical masses and transport such masses dorsally into the dorsal groove which carries the collected masses backwards into the digestive tract. Thus the ciliary mechanisms on a gill-bar of Amphioxus are exactly the same as those on the gill-filaments of some Lamellibranchs, as Pecten, and some Gastropods, as Crepidula. A subsidiary mode of food-collection is effected in the buccal cavity of Amphioxus by the ciliated tract known as the wheel organ, and Hatchek's pit, which supplies mucus for entrapping food-particles. These particles are passed on to the peri-pharyngeal bands which, conduct them in turn into the dorsal groove. The gill of Amphioxus functions mainly as a feeding organ and a water pump, and probably not at all as an organ for aerating the blood. The mode of feeding in Ascidians is almost exactly the same as that described above for Amphioxus. Food-collection, however, in Ascidians is effected by cilia on the papillae and similar outgrowths on the gill, and is also helped in some forms by transverse waving of the longitudinal bars, by which process the food is pushed as well as lashed towards the dorsal region of the pharynx.

CANADIAN GALLS AND THEIR OCCUPANTS—AULAX NABALI, N. S

Gall at the base of the stem of Nabalus altissimus, usually in masses surronding stem, often extending down on main root, rarely on main fibres of root, usually about an inch under the ground, sometimes partly above the ground. Galls roughly spherical, 5 mm.—10 mm in diameter each containing 1–10 cells, usually aggregated in irregular cylindrical masses of 2–14, resembling small knobby artichokes or irregular small white potatoes.

Note on a Deposit of Middle Pleistocene Gravel in the Worden-Hall Pits, near Leyland, Lancashire; and on a Collection of Shells and Fragments of Shells found there by Miss M. H. Ffarington

About a mile from the Leyland station, on the east side of the Bolton and Preston railway, there is an extended flat-topped hill of small elevation, which has for many years past been the chief or only source of supply for a considerable district, of coarse and fine road-gravel. The pits from which the gravel is got have been worked from the eastward. The material is screened and sorted on the ground, the stones and gravel carried away, and the refuse left to fill up holes. At present the exposed section of the hill is seen in two large excavations as a face some 40 or 50 feet in height, of which the upper 10 feet consists, under the sward, of yellow brick-clay. The remainder of the face exhibits a thick bed, 30 to 40 feet thick, of marine gravel (shingle) and sands, very rarely showing any clayey admixture. The gravel consists of pebbles of a very large variety of rocks, ranging in size from that of a cylindrical mass 8″ by 18″ down to that of coarse and fine shingle and sand. There are occasionally small layers, of slight extent and thickness, of fine sea-sand; and the whole mass rests on a bed of the same sort of sand, the depth of which has not yet been ascertained.

XV. On the thermodynamic theory of waves of finite longitudinal disturbance

§ 1. The object of the present investigation is to determine the relations which must exist between the laws of the elasticity of any substance, whether gaseous, liquid, or solid, and those of the wave-like propagation of a finite longitudinal disturbance in that substance; in other words, of a disturbance consisting in displacements of particles along the direction of propagation, the velocity of displacement of the particles being so great that it is not to be neglected in comparison with the velocity of propagation. In particular, the investigation aims at ascertaining what conditions as to the transfer of heat from particle to particle must be fulfilled in order that a finite longitudinal disturbance may be propagated along a prismatic or cylindrical mass without loss of energy or change of type: the word type being used to denote the relation between the extent of disturbance at a given instant of a set of particles, and their respective undisturbed positions. The disturbed matter in these inquiries may be conceived to be contained in a straight tube of uniform cross-section and indefinite length. § 2. Mass-Velocity .—A convenient quantity in the present investigation, is what may be termed the mass-velocity or somatic velocity —that is to say, the mass of matter through which a disturbance is propagated in a unit of time while advancing along a prism of the sectional area unity. That mass-velocity will be denoted by m .

I. On the laws and principles concerned in the aggregation of blood-corpuscles both within and without the vessels

In 1827, or forty-one years ago, the phenomenon which forms the subject of this paper was first observed by Mr. Joseph Jackson Lister and the late Dr. Hodgkin. To these observers the microscope revealed the fact that if a minute drop of human blood is placed between two plates of glass, the red corpuscles apply themselves to each other by their concave surfaces in such a manner as to form long cylindrical masses, which resemble piles of coin, and that very frequently these piles are so arranged as to form with each other a complete network of rouleaux with clear intervening spaces occupied by liquor sanguinis.

On the formation of cylindrical masses of snow in Orkney

On the formation of cylindrical masses of snow in Orkney

On the formation of cylindrical masses of snow in Orkney

On the formation of cylindrical masses of snow in Orkney