IC2 



SCIENCE-GOSSIP. 



the course of twenty-four hours a second layer, 

 keeping the cement far enough over the cover-glass 

 so as to hide the ring underneath. When the 

 zinc cement has set quite hard, the slide should 

 be finished in Brunswick black, to which ten to 

 twenty per cent, of japanner's gold-size has been 

 added. It is better, when finishing the cells with 

 the zinc cement and Brunswick black, to first 

 place the turntable at an angle, and do the side 

 and base, then place the table level and do 

 the top. 



In putting on the Brunswick black a ring of the 

 white cement should be left exposed on the top of 

 the cell next the centre, all the rest being covered 

 with the black. This, if neatly done, will give a 

 very pretty appearance to the slide, the black 

 cement contrasting well with the white of the 

 opal glass on one side, and the white cement on 

 the other. I also invariably add about twenty 

 per cent, of Canada-balsam additional to the zinc 

 white bought from opticians, as I find if used as 

 bought it is too brittle. 



The forms of so many of our flower-seeds, both 

 wild and cultivated, as well as the peculiar markings 

 to be found on them, when examined by the 

 microscope, are indeed wonderful, and most 

 interesting. To look at the tiny black or brown 

 dust, as it may appear to the unassisted eye, 

 one could hardly credit the beauty and form which 

 lie there concealed. It is only when we apply the 

 microscope and plenty of light that we can see the 

 gorgeous array in which nature has clothed so 

 many of our seeds. Poppies, ragged robin, chick- 

 weeds, stitchworts, catchflies, soapworts, foxglove, 

 sundews and orchids are all notable for the 

 beauty and variety of their seeds. Few prettier 

 objects can be examined than the seeds of these 

 plants — and many others besides — when properly 

 mounted. 



There is also much yet to be learned from a 

 study of flower-seeds. One of the first things 

 which impresses itself on an observer is that there 

 seems, with few exceptions, to be no particular 

 design or plan, or what might be called a connecting 

 link between the various forms of seeds in regard 

 to their markings. Nature seems to have taken 

 her honours in her hand and scattered them 

 broadcast, here, there and everywhere, among seeds 

 from the lowest to the highest, without any regard 

 to order or class. In one genus we find a species 

 with beautifully marked seeds, and alongside of 

 it another species with seeds quite smooth and 

 plain. How should this be so ? There must be a 

 reason for it ; so here is an opportunity for some 

 young botanist to excel in finding out the cause. We 

 cannot doubt but that these markings and peculiar 

 shapes are of some benefit to the plants possessing 

 them. In the order Compositae we see clearly the 

 benefits which its species derive from the special 



forms of many of its seeds. In this order we find 

 seeds which, in addition to the calyx hairs adher- 

 ing to them, are also provided with barbs and hairs 

 which must be of great assistance in helping them 

 to find their way into the soil after they have been 

 dispersed far and wide by the winds. As a conse- 

 quence of this special adaptation of the seed we 

 find the order to contain no fewer than 10,000 

 known species, as compared with 5,000 of the 

 Orchidaceae, which comes nearest to it in numbers. 

 Of course, other advantages as well as the forms 

 of the seeds have enabled the plants of this order 

 to be so numerous, but probably its seeds have 

 more than anything else to do with it. It is, 

 however, when we come to consider the markings 

 and forms of seeds in other orders that the difficulty 

 of ascertaining their uses appears. For instance, in 

 Leguminosae we have an order with most of its 

 seeds smooth or nearly so, and yet its species num- 

 ber about 4,700. In Caryophyllae, which we may 

 safely say has the prettiest marked seeds, we have 

 an order with only Soo species. It is when we are 

 confronted by facts such as these that we wonder 

 what are the real uses or benefits of the pittings, 

 wrinkles and reticulations of seeds as compared 

 with those which are smooth. 



Again, smooth or marked seeds are not confined 

 to particular sections of orders or genera, or to 

 plants growing in particular habitats or flowering 

 at any particular time. Take for example the 

 genus Geranium, where' we find six out of the 

 twelve British species described in Hooker's 

 "Student's Flora of the British Islands'' (third 

 edition) have smooth seeds and the other six have 

 marked ones. Neither are the smooth or marked 

 seeds confined to any particular section or to 

 plants growing in particular habitats. In the 

 perennial section we have G. sylvatimm, G. pratense 

 and G. pcrenne, all of which grow in meadows; yet 

 we find that the first two of these species have 

 reticulated seeds and the latter smooth. Or take 

 G. molle and G.ptsillimi, both of which have smooth 

 seeds, whereas G.rctundifolium, G. columbinnm and 

 G. dissectum all have pitted seeds, and these five 

 species are to be found growing principally about 

 waste places. Neither does their distribution help us 

 any more, as G. columbinnm, with its pitted seeds, has 

 the smallest range in Britain of these five species ; 

 while G. molle and G. dissectum, two common ones, 

 one with marked seeds and the other plain, are 

 about equally distributed. I could go on multiply- 

 ing instances such as these, for there are many 

 such, but the above is sufficient to show the 

 difficulties to be encountered in arriving at any 

 reasonable conclusion as to the benefits plants 

 derive from the markings and forms of their seeds ; 

 but that they are of some use to the plants possess- 

 ing them we may rest assured. 

 Rothesay. 



