INTEOBTJCTION. 33 



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 aU their 

 characters, but these transitions are not all observable in the same specimen. 

 The observation of a single intermediate is therefore of little value, unless it 

 be one link in a long series of intermediate forms, and, when met vsith, 

 should lead to the search for other connecting Unks. 



2. Accidental aberrations fiom the ordinary type, that is, those of which 

 the cause is unJcnown. 



These require the more attention, as they may sometimes lead the be- 

 ginner far astray in his search for the genus, whilst the aberrations above 

 reduced more or less to general laws affect chiefly the distinction of species. 



Almost all species with coloured flowers are Uable 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 aU, either to the flowers produced at particular seasons, or 

 to aU the flowers of individual plants, or the petals may be reduced to nar- 

 row shps. 



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

 less of their irregularity. Spurs may disappear or be produced on aU, in- 

 stead of only one of their petals. 



One part may be occasionally added to or subtracted from the usual 

 number of parts in each floral verticil, more especially in regular polypeta- 

 lous flowers. 



Plants usually monoecious or dioecious may become occasionally herma- 

 phrodite, or hermaphrodite 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 distiiictions. 



