120 



CASSELL'S POPULAR GARDENIXG. 



or « prothallus." (See Figs. 1, 2, p. 49, Vol. I.) These 

 plates are not, as is usually thought, the seedling 

 Ferns, but correspond more nearly to the flower-stalk 

 of any ordinary plant, because, as a matter of fact, 

 they bear the true flowers of the Fern on their under 

 surface. To see these, a compound microscope is 

 essential, and with this aid, two 

 difi'erent kinds of " flowers," 

 so to speak, may be seen, both 

 made up of cells, the one glo- 

 bular in form, the other tubu- ■ 

 lar, and resembling a chimney 

 or hollow cylinder (Fig. 62). 

 In the globular bodies, which 

 are called "antheridia" (Fig. 

 63), are formed very minute 

 fragments of protoplasm, coiled 



up spirally, and provided at one end with two bris- 

 tles of extreme tenuity. These are the " anthero- 

 zoids'' (Fig. 64). At the bottom of the tubular flowers, 

 called " archegonia," is a cell 

 called the " central cell," and 

 containing the mass of proto- 

 plasm or " oosphere," which will 

 develop after fertilisation into the 

 young Fern (Fig. 65) , The process 

 of fertilisation is effected by the 

 passage of the antherozoid from 

 the male flower into the cavity of 

 the female flower, where it comes 

 into contact with the central cell, and either directly 

 or indirectly with the "oosphere" in its interior. 



This latter, thus stimulated into action, becomes 

 invested by a cell-wall, di\ddes, sub- 

 divides, and ultimately forms a new 

 plant, the true seedling Fern. The chim- 

 ney - shaped " flowers " are thus the 

 females, the globular ones are the males, 

 and both as a rule occur on the same 

 prothallus. The prothallus we have seen 

 issues from the spore, and may be likened 

 to a detached bud which extends into a 

 shoot bearing flowers. Here, then, we have 

 the process of true reproduction, consist- 

 ing of the union of one mass of proto- 

 plasm (the spermatozoid) with another 

 (the "oosphere"), and as a result, the de- 

 velopment of the latter into a new plant. 



strictly con-espondent with the oosphere of the Fern^ 

 and when acted upon by the pollen, it di\'ides, 

 subdivides, grows, and develops into a new plant, 

 the embryo plant. But the flowers of flowering 

 plants are borne on ordinary branches, and not on 

 separately formed prothalli.. The prothallus stage 

 then, which is so marked a 

 feature of Ferns and of the 

 higher Cryptogams, generally, 

 is absent in the flowering 

 plants, and is only visible in 

 the form of rudiment in the 

 Pines and Cycads. 



Autlieridia (biglily magnified). 



Antlierozoids (highly magnified). 



rig. 65.— Single Arche- 

 gonia (highly magni- 

 fied) , showing passage 

 of the antherozoids. 



-The Reproduction of Flowering Plants. 



— The process of reproduction in the so - called 

 " flowering plants " is in many points essentially 

 similar to that of the Fern above mentioned. The 

 antherozoids are represented by the pollen-grains of 

 the flower contained in the anther; the "oosphere" 

 contained within the embyro sac of the ovule is 



Flowers and their 

 Uses. — The word " flower " 

 has hitherto been used in its 

 proper meaning as applied to the true reproductive 

 organs and the cases ia which they are enveloped. 

 But this is not the popular signification of the word 

 flower. In fact, in most flowers 

 WL there are some parts that are 

 essential, an(i these are of course 

 the organs of reproduction ; and 

 other parts that are mere acces- 

 sories, not essential, though not 

 without their use, as we shall 

 hereafter see. In most boolcs 

 it is the custom to speak of the 

 accessories flrst, and inasmuch as 

 they are only modifications and adaptations of the 

 leaves, which pass more or less gradually into them, 

 there are good grounds for so doing ; but from our 

 present point of ^'iew it may be desirable 

 to begin with the essential, and to post- 

 pone the consideration of the accessory 

 organs. 



Every one knows and admires the in- 

 finite -^-ariety in the shape and appearance 

 of flowers, and it might seem at first sight 

 a hopeless task to attempt to i-educe all 

 these varied forms to a few simple ar- 

 rangements, and find a use and a purpose 

 for all these seemingly capricious and 

 endless permutations. Nevertheless in no 

 department of Natural History are order, 

 method, and adaptation to purpose more 

 strikingly exemplified than in the case of 

 flowers. The botanist has the clue to the 

 seeming mystery ; he unravels its history in the past, 

 pursues its course in the present, divines the why 

 and the wherefore, and lays the knowledge he has 

 gained before the practical man, for him to turn to 

 good account, in so far as his requirements are con- 

 cerned. In this place we must confine ourselves to 

 one or two examples which must serve to illustrate 



