HARDWICKE'S SCIENCE-GOSSIP. 



57 



of botany, and the case is something like this. Thou- 

 sands before Galileo had observed the stately swing 

 of the great brass chandelier in the cathedral at Pisa, 

 and thousands before Newton had noticed the fall of 

 an apple on a chill October day ; thousands before 

 James Watt had watched a boiling kettle, and thou- 

 sands had seen bees flitting about the flowers of the 

 orchis and loosestrife ; but it took the perseverance 

 and genius of Darwin, to unravel the mysterious 

 mechanism of this curious plant. It is strange now 

 to read the remarks made about the fertilisation of 

 the common orchis prior to the year 1862 : some 

 said that it is fertilised by absorption, while others, 

 carrying their ideas to the excess of caution, declared 

 that it was one of those unexplained secrets of nature 

 into which it was not proper to pry. 



The term inflorescence is applied to the general 

 arrangement of flowers on a stem, which is managed 

 in such a variety of clever ways that plain evidence 

 of more than human resource and invention is given 

 in bold characters. Take, for instance, a spike of 

 the common orchis and a flower of the common 

 buttercup ; the inflorescence of the one is the exact 

 opposite of the inflorescence of the other. The 

 buttercup is of primitive type, centrifugal, and with 

 leaves developed : the orchis is highly modified, 

 centripetal, and with leaves plain. In the buttercup 

 (" Science Primer," p. 54), the flower that terminates 

 the axis of the plant opens first, then the one next to 

 it, and so on, until the flower farthest from the first 

 has opened. Such inflorescence is called centrifugal, 

 because the order of flowering is from the central 

 axis outward, and the axis itself does not elongate. 

 In the orchis, the flower farthest from the top opens 

 first, then the next, and so on, till the one at the ex- 

 tremity of the spike is reached ; and all this time the 

 axis is elongating. The teazel is different again, 

 for it opens its flowers first half-way up the head, 

 and then works upwards and downwards. 



Here the very natural question may be asked : Why 

 should two common flowers, which come out about 

 the same time, have exactly opposite arrangements ? 

 The answer happily is simple enough : the two 

 flowers have two very different offices to perform. 

 The buttercup supplies a vast amount of pollen, and 

 the orchis supplies what ? That's the question ! That 

 has been the object of these observations, to answer 

 the question : What does the orchis produce necessary 

 to secure the visits of bees ? With your permission, 

 I will proceed very leisurely at this point of the 

 inquiry, like a gossamer-spider feeling tremblingly 

 along its line. 



A full-grown orchis-spike shows many sessile, 

 irregular, labiate, ringent flowers, duly arranged one 

 above the other. The process of opening, which is 

 here only just begun, takes about a fortnight, so that 

 allowing a fortnight for the ripening of the pollen, 

 the entire period occupied in unfolding a spike is 

 about a month. Durins: this time the flowers remain 



open, bidding for insect-services night and day, for 

 an orchis-flower, unlike the marigolds and sun-eyed 

 daisies, that close their winking flowers in rain, is 

 incapable of closing again after having once opened ; 

 but as soon as the ovary has been impregnated, the 

 flower, having performed its office, fades away, and 

 if the spike is a large one, the lower flowers are dead 

 before the upper ones are expanded. Next, look at 

 the delicate poise of the flower ; it is fastened like a 

 spring. This provision is necessitated by the state of 

 the case, for as the flowers cannot close when once 

 open, it is manifest that the wet and heavy dews 

 would soon spoil the pollen if the corolla faced up- 

 ward, and it harmonises also with the centripetal 

 inflorescence ; for it would be inconceivable that a 

 flower should be made in such a way that a bee 

 visiting it would be subjected to the inconvenience of 

 flying backwards, as would occur if the inflorescence 

 were centrifugal. Our examination, then, has not 

 extended far before we see how eminently an orchis 

 is adapted for the visitation of insects ; and, even if 

 we were not familiar with all the deeply interesting 

 facts about the order, I think the above could not 

 escape notice. 



(To be continued.) 



THE PRE-CAMBRIAN ROCKS OF ENGLAND 

 AND WALES. 



By W. W. Watts, B.A., F.G.S. 



THE study of the Pre-Cambrian rocks of England 

 was for many years neglected and even ignored, 

 from the time when Murchison declared that it was 

 not possible for such rocks to occur there. He 

 worked out to some extent the great gneissose rocks of 

 the north-west Highlands, and not finding some of 

 their characteristic details repeated in the Malverns 

 he concluded that the gneisses of that place were 

 merely altered Cambrian rocks, and thought that he 

 was confirmed in this conclusion by the fact that the 

 strike of these gneisses agreed with that of the flank- 

 ing Cambrian deposits. The value of this we shall 

 estimate later. 



In spite of this assertion from the lips of the 

 director-general of the Geological Survey, many men 

 believed that we had in England and Wales 

 representatives of these very ancient rocks, and 

 amongst them I may mention Mr. W. S. Symonds, 

 who, writing in 1872, in "Records of the Rocks," 

 states his belief that the crystalline rocks of Anglesey 

 and Caernarvon, the schists of Holyhead, the rocks of 

 Bardsey, and of the Lleyn or Caernarvon peninsula 

 will all eventually be classed as Pre-Cambrian ; he 

 continues and includes in this statement the Twt Hill 

 rock of Caernavon, the syenitic axis of St. David's, 

 and the Malvern gneiss. How far his ideas were 

 correct this paper will endeavour to show, and we 



