21 



this purpose the lip is commonly in the front of the flower, 

 directed downwards and outwards, which position is caused by a 

 remarkable twisting of the ovary at the time the flower is opening. 

 It is thus turned half round, and the lip, which should occupy the 

 back and uppermost part of the flower, becomes the lowest a 

 very remarkable arrangement, when it is considered in conjunc- 

 tion with the many other marvellous adaptations of the lip to 

 favour insect visitors. Malaxis paludosa is an extraordinary 

 exception ; for in this the flower is twisted wholly round, and the 

 lip thus assumes its normal position. In some other exceptions 

 the lip is uppermost, as in Disa grandiflora and certain of the 

 Angraecums, particularly A. eburneum. 



The lip is often prolonged at the base into a spur or nectary of 

 various lengths, from slight depressions, as seen in the Dendro- 

 biums and others, to the wonderful Madagascar orchid, Angrascum 

 sesquipedale, with a spur frequently exceeding a foot in length. 

 So commonly does the nectary of orchids appear to offer tempta- 

 tions to insects, that Mr. Darwin ventured to suggest the probability 

 some moth, or similar creature, being concerned in its fertili- 

 sation, and possessing for the purpose a proboscis of sufficient 

 length to reach the nectar at the lower part of the spur. As no 

 insect was known at the time with a trunk of such length, the 

 opinion was received rather incredulously, but since it first ap- 

 peared a moth has been found in Brazil with a proboscis over loin, 

 long, so that it does not now appear so unlikely to be correct. Nectai 

 is secreted in considerable quantities by some orchids, but, in re- 

 ferring to this matter, this author just named has observed that, 

 " Although the secretion of nectar is of the highest importance 

 to orchids by attracting insects, which are indispensable to the 

 fertilisation of most of the species, yet good reasons can be 

 assigned for the belief that nectar was aboriginally an excretion 

 for the sake of getting rid of superfluous matter during the 

 chemical changes which go on in the tissues of plants, especially 

 whilst the sun shines." The reason assigned is the production 

 of nectar by parts of the flower which have no influence upon the 

 fertilisation. 



THE COLUMN AND POLLEN MASSES, 



As already remarked, the column in orchids is a very peculiar 

 organ, and well deserves the attention of all who are interested in 

 the wonderful structure of the vegetable kingdom. It is a com- 

 bination of stamens and pistil, quite distinct from what occurs in 

 any other family of plants, though an approximation to it is seen 

 in the Birthwort, Aristolochia Clematitis, but in that the anthers, 

 with their pollen, are of the usual character, and are equally dis- 

 posed round the top of the column. In the orchids the column is 

 a more or less fleshy body, from very minute proportions to 



