SCIENCE-GOSSIP. 



133 



colourless fluid. The nucleus is also carried slowly 

 along in this movement, which, when the proto- 

 plasm has become converted into a mere network 

 of cords, has the appearance of a system of reticular 

 currents. This movement of the protoplasm ceases 

 in most cells before they are full-grown ; but in 



Fig. 2. — Cells from the Spathaceous Bract of 

 Hydrocharis morsus-ran*, x. 400. 



many aquatic plants, even of the class Phanero- 

 gamia, the protoplasm does not become excavated 

 in the same way as it does in the cells of hairs, etc., 

 but applies itself as a thick layer upon the inside of 

 the cell-walls, and, retaining its activity, performs 

 a rotatory movement around the wall of the cell 

 permanently. In Chara, the moving layer of proto- 

 plasm is not applied upon the cell-wall ; the 

 primordial utricle, with the chlorophyll corpuscules 

 imbedded in it, lies on the cell-wall motionless ; 

 and a thick mucilaginous layer, situated between 

 this and the central cavity filled with watery cell- 

 sap continually circulates. 



This circulation in reticulated currents is most 

 easily observed in young hairs of higher plants. 

 The movement of the parietal layer of protoplasm 

 is made very visible in the leaves of Vallisneria by 

 the green chlorophyll corpuscules imbedded in it, 

 and it may be well seen in Anacharis, in the 

 delicate tissues of Hydrocharis, Stratiotes, etc. It 

 occurs in the rootlets and other parts, as well as 

 in the leaves. The phenomenon is most strikingly 

 shown in the Characese, especially in the Nitella;, 

 which are simpler and hence more transparent 

 forms. This movement is only affected by 

 substances that injure the healthy condition of the 

 structure, such as chemical agents producing 

 bursting or solution of the tissue, heat sufficient to 

 cause coagulation or solution of contents, etc. In 

 Chara, the large cells may be tied across, and 



yet the circulation be set up again in each of the 

 chambers thus formed. Electrical currents do not 

 affect it. The movements in the protoplasm are 

 attributed to various causes, such as contraction of 

 certain portions of it, varying degrees of imbibition 

 in different portions of the mass, the alternations in 

 this wise giving rise to the currents. In many 

 cases it has been definitely proved that the move- 

 ment of the juices in which chlorophyll granules 

 are contained is directly dependent on the agency of 

 light, especially of the more highly refrangible rays 

 of the spectrum, Under the influence of diffused 

 light the chlorophyll granules range themselves 

 parallel to the surface; but under that of direct 

 light they are disposed on the lateral walls of the 

 cells." 



43a, Brecknock Road, London, N .W. ; May lyth, 1894. 



MOCK SUNS. 



By the Rev. Samuel Bareer. 



/^\N Wednesday, July nth, I observed, from 

 ^ West Newton, Aspatria, Cumberland, the rare 

 phenomenon of the solar halo of go c attended by 

 mock suns in several different positions. The 

 large halo, gg in the sketch, intersected the primary 

 or ordinary halo of 6o° laterally, making a clear 

 sweep round the heavens, enclosing the zenith (x) 

 and passing right over the disc of the sun (s). 

 The mock suns were not well defined, and were in 

 the positions marked r in sketch. The halo of 6o° 

 was intensely brilliant in colouring, much more 

 than in an ordinary rainbow ; blue and orange 

 predominated. The great halo, marked gg in 

 sketch, was of a uniform greyish-blue tint in all its 

 length, even where it passed the sun. The only 





Solar Halo of go" and Mock Suns. 



place where it showed any prismatic effect was at 

 a point in the north-west, directly opposite the 

 sun. It was much narrower than the primary 

 halo, and formed a perfect circle. There was a 

 high drift of light cirrus and cirro stratus. The 

 phenomenon was visible from 9.10 a.m. to 1 p.m., 

 the primary halo longer. The greyish tint of the 

 great halo probably indicates the great height of 

 the ice-crystals that originated it. A clearly 

 defined line gave a crescent form to the east and 

 west sides of the first halo, a fact hard to explain. 

 West Newton, Aspatria, Cumberland ; July, 1894. 



