414 



SCIENTIFIC NEV\rS. 



[May 4, i5 



sp. (fig. 13), in which the surface of the shell is decorated 

 by delicate spines and the primary chamber armed by a 

 long stouter one. The specimen is from the London clay of 

 Piccadilly. It has also been found in the Pliocene of Kar 

 Nicobar and in Miocene beds. CristcUaria cultrafa, Montf. 

 sp. (fig. 14), is a form consisting of a series of modified 

 Lageniform chambers, wrapped spirally and partly em- 

 bracing those first formed. This variety, from the Gault 

 of Surrey, has a beautifully translucent keel border- 

 ing the shell. This form is also found in recent soundings. 

 In Uvigerina the shell consists of a triple series of 

 chambers coiled spirally to produce an elongated form. 

 The specimen of U. asperula, Cz. (fig. 15), from the 

 London clay of Piccadilly, has its surface covered with 

 minute prickles, and the primary chamber commences 

 with a spine. It is found rather plentifully, both fossil 

 and recent. 



The form next taken is Globigerina bulloidcs, d'Orb. 

 (fig. 16), a shell composed of a series of Orbuline or 

 more or less spherical chambers arranged in a helicoid 

 spiral. The inferior side with the aperture is shown 

 in the right-hand figure. This type constitutes the 

 greater part of the chalky ooze dredged from the Atlantic. 

 The same form, but smaller in size, is found numerously 

 in the white chalk. Rotaliabcccarii, Linne sp. (fig 17), is 

 found commonly in many recent shore deposits of Britain 

 and elsewhere. It is found also fossil in beds of Miocene 

 and Pliocene ages ; in the Chillesford Crag it occurs very 

 diminutive in size. Polystomella crispa, Linne sp. (fig. 18), 

 is a shell which may be found like the preceding in 

 British shore gatherings but much more abundantly. 

 This shell exhibits on the exterior the last whorl of 

 chambers only. 



Having thus taken a few examples from the almost 

 endless variety of aspects which these shells present we 

 may wish to study the Foraminifera by actual compari- 

 son. There will be no difficulty in procuring material upon 

 which we may work, as deposits occur in nearly every 

 stratum of any extent in sedimentary rocks, including 

 shelly clays and fimestone beds. Very frequently the 

 oolitic Umestones when examined in thin sections, show 

 each individual grain with its nucleus formed by a Fora- 

 minifer. The shells may also be obtained from dredgings 

 or soundings taken at almost any depth ; and at some 

 stations the calcareous sand consists of a nearly pure 

 assemblage of them. Along our own coasts foraminiferal 

 sand may be procured either by dredging or by collecting 

 the material which has been stranded on shore by the 

 ebb tide. 



Walking along a sandy shore during the receding tide 

 one will generally discover a series of parallel streaks 

 left on the sand, striking the notice of the observer by 

 their arrangement in alternate black and white lines. If 

 this white portion be scraped up and examined it will be 

 seen to consist of little else than very clean specimens of 

 Foraminifera, with perhaps some spines ot echinoderms, 

 valves of ostracoda, fragments of polyzoa, and minute 

 shells of mollusks. The black portion may be ignored, 

 as that will be found to consist of particles of carbonized 

 seeds, fragments of seaweed, and chips of coke from the 

 furnace of some passing steamer. In collecting recent 

 Foraminifera in this way it is very noticeable that these 

 shells occur in greatest numbers on limestone or chalk- 

 bound coasts, as, for example, along the shores of Sussex 

 and Kent where entirely pure gatherings may often be 

 taken. On the other hand, in the vicinity of land desti- 

 tute of limestone rocks, the material left by the side may 



consist almost entirely of seeds or seaweed fragments ; 

 clearly indicating how the dissolution of the carbonate of 

 lime by carbonated waters and its separation by these 

 tiny animals from the water work together. 

 (To be co?itinued.) 



THE WINTERING OF WATER WEEDS. 



THE writer has had under observation during the past 

 winter a number of water weeds, including Utri- 

 cularia, Myriophyllum, and Hydrocharis. In October 

 they had spread out into a great tangled mass, floating in 

 or upon the water. As the cold weather came on, the 

 buds at the ends of the branches ceased to expand, then 

 the older stems and flowers began to wither. At 

 Christmas the appearance of the plants may be described 

 thus : — Hydrocharis had sunk to the bottom and dis- 

 appeared ; Utricularia and Myriophyllum had turned to 

 a greenish-grey colour, and had become extremely fragile. 

 The terminal buds were of a bright green colour, very 

 closely wrapped, and dragged down to the bottom by the 

 sinking of the old stems. As spring came on, the 

 withered plants broke up completely, and formed a soft 

 grey film overlying the bottom. The slightest disturb- 

 ance was now enough to break up the decayed mass and 

 liberate the buds, which then floated upwards. Here 

 and there detached buds of Hydrocharis began to reappear 

 on the surface in the same way. 



Flotation in all these plants is provided for by air 

 cavities, which occupy the hollow joints of the stem. It 

 is easy to demonstrate the existence of such cavities 

 by teasing out a bit of stem in water under the micro- 

 scope. Tiny air-bubbles are disengaged in large numbers. 

 A carefully prepared cross-section shows a large and 

 simple cavity. If an old and decaying stem is teased out 

 in the same way, no air escapes ; it has become water- 

 logged. Since the plant is not, as a rule, in direct 

 contact with the air, we must suppose that the air is 

 secreted by the tissues. Probably it is not ordinary air 

 at all, but oxygen. No doubt it is continuously formed 

 while the tissues are green and active. When the 

 season of growth is passed, and little assimilation of 

 carbon dioxide takes place, the supply of oxygen is cut 

 off', and the plant sinks to the bottom. It will be seen 

 that the process of natural decay is thus turned to good 

 account by water weeds, which employ it to shelter 

 themselves from the action of frost, and also to multiply 

 the centres of growth by setting free a great number of 

 terminal buds. 



-•-^S^>^5ef-t — ■ 



Influence of the Moon upon Vegetation. — M. G. 

 Delaunay, an inspector of forests, delivered recently a 

 lecture on this much-disputed subject. Ciel et Torre gives 

 an abstract of his discourse from the Revue des Eaiix et 

 des Fords. Referring to the notion that it is unwise to 

 plant during the time of new moon, he said, that as far 

 as forest-trees and fruit-trees were concerned this opinion 

 was supported neither by theory nor by practice. As to 

 herbaceous plants, and in particular pot-herbs and salads, 

 it is alleged that the young plants are eaten off by slugs. 

 He suggests that at near full moon the small grey slug, 

 which loves darkness, may not come out so much to feed. 

 He thinks that the soundness of timber is affected not by 

 the phase of the moon at the time of felling, but by the 

 season of the year. 



