THE YOUNG NATURALISE 



149 



the " rathe primrose " that the typical soul 

 lin which all poesy is dead is pilloried by 

 Wordsworth in the well-known lines . — 



• A primrose by the river's brim, 



Or by the cottage door, 

 A yellow primrose was to him. 



And it was nothing more." 



Familiar as the flowers of the primrose 

 are, there are yet peculiarities in its structure 

 which are doubtless overlooked by multi- 

 tudes who gather them. More than 100 

 fyears ago a botanist had observed and noted 

 :hat of the flowers of primrose about one-half 

 aad the anthers seated at the top of the tube 

 ")f the corolla, almost closing its throat, 

 whilst the style and stigma only reached 

 libout half way up the tube ; whereas in the 

 other moiety of plants the style reached to 

 :he top of the tube, the stigma like the head 

 ->f a pin showing at the aperture, whilst the 

 mtht-rs are inserted half-way down. So that 

 n the one form the stamens are on a level 

 a ith the stigmas of the other (see plate). 



Growers of auricula and polyanthus had 

 loticed the same peculiarity, and gave the 

 lame of " thrum-eyed " and " pin-eyed " to 

 :he different forms, and by this name the 

 listinction is noted by children in the north 

 )f England, who string necklaces of the 

 lowers of primroses and cowslips by pushing 

 he tubes of the flowers into each other, and 

 is the ' pin-eyed " form has the tube wider 

 "or half its depth they are most in request 

 "or this operation. 



Like many more so-called trivial phenomena 

 |jf nature which are unthinkingly seen without 

 being observed, till some master-mind fur- 

 bishes the key to unlock the secret. So it 

 A'as reserved for Mr. Darwin to present a 

 solution of the use of this diversity of 

 Structure. By a series of exhaustive experi- 

 | nents, which we have not space to reproduce, 

 be has shown that in order to ensure full 

 fertility the pollen of one primrose has to be 

 parried to the stigma of another flower on a 

 different plant; and not only so, but the 

 X)llen of the short styled form must be con- 

 veyed to the stigma of the long styled form 



in order that the greatest number of seeds 

 producing the most robust plants may be 



' procured. As will be seen from the diagram, 

 there are four different ways in which 

 fertilisation may be accomplished. Two of 

 these may be called illegitimate when the 

 pollen of a flower may be applied to its own 

 stigma, which produces a small quantity of 

 seed, or none at all. And the other, or legit- 

 imate union, when the pollen of one flower is 

 carried. to the stigma of another at the same 

 height. This is accomplished by the aid of 

 insects, such as large humble bees and moths. 

 It will readily be understood that a bee in 

 search of food, thrusting its proboscis into 

 the tube of a primrose or cowslip, will dust 

 its proboscis with pollen at the top or half 

 way down, which will be carried to the next 

 rlower it visits, when some of it is certain to 

 adhere to the stigma which stands at the same 

 level. In the case of primroses this process 

 is accomplished by moths only ; for close ob- 

 servation has never yet detected the visits of 

 bees to primroses, although they frequent 

 cowslips, and are mainly instrumental in 



, fertilising them. So dependant are cowslips 



: on the visits of bees that if their visits are 



t 



j effectually excluded by the plants being 

 covered with nets, no seeds will be produced 

 at all. The pollen grains from the short 

 styled are conspicuously larger, and different 

 ' in shape, from those of the long-styled form, 

 J being also much more potent in their effect. 



We have here the strange spectacle of a 

 ! hermaphrodite flower with both organs de- 

 J veloped, but gradually assuming a unisexual 

 j character as to function. Both forms are 

 nearly equally common in nature, but they 

 J never merge into each other, so that there is 

 no mistaking to which class any individual 

 plant may be referred, and if a plant is fer- 

 ! tilised with its own pollen it will produce 

 plants all of one form, viz., its own. 



The term dimorphic is applied to plants 

 I such as the primrose and cowslip, in which 

 the styles are of two different lengths, and 

 such forms are not uncommon. A much 



