xxviii OUTLINES OF BOTANY. 



Where two supposed species grow together, intermixed with numerous intermediates bearing 

 good seed, and passing more or less gradually from the one to the other, it may generally be 

 concluded that the whole are mere varieties of one species. The beginner, however, must be 

 very cautious not to set down a specimen as intermediate between two species, because it appears 

 to be so in some, even the most striking characters, such as stature and foliage. Extreme 

 varieties of one species are connected together by transitions in all their characters, but these 

 transitions are not all observable in the same specimens. The observation of a single inter- 

 mediate is therefore of little value, unless it be one link in a long series of intermediate forms, 

 and, when met with, should lead to the search for the other connecting links. 



2. Accidental aberrations from the ordinary type, that is, those of which the cause is unknown. 



These require the more attention, as they may sometimes lead the beginner far astray in his 

 search for the genus, whilst the aberrations above-mentioned as reducible more or less to 

 general laws, affect chiefly the distinction of species. 



Almost all species with coloured flowers are Ijable to occur occasionally with them all white. 



Many may be found even in a wild state with double flowers, that is, with a multiplication of 

 petals. 



Plants which have usually conspicuous petals will occasionally appear without any at all, 

 either to the flowers produced at particular seasons, or to all the flowers of individual plants, or 

 the petals may be reduced to narrow slips. 



Flowers usually very irregular, may, on certain individuals, lose more or less of their 

 irregularity, or appear in some very different shape. Spurs, for instance, may disappear, or be 

 produced on all instead of one only of the petals. 



One part may be occasionally added to, or subtracted from, the usual number of parts in each 

 floral whorl, more especially in regular polypetalous flowers. 



Plants usually riionoecious or dioecious may become occasionally hermaphrodite, or her- 

 maphrodite plants may produce occasionally unisexual flowers by the abortion of the stamens or 

 of the pistils. 



Leaves cut or divided where they are usually entire, variegated or spotted where they are 

 usually of one colour, or the reverse, must also be classed amongst those accidental aberrations 

 which the botanist must always be on his guard against mistaking for specific distinctions. 



