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in coming out as before. After the pollen masses are deposited 

 upon the stigma of an orchid, minute tubes are emitted as in 

 ordinary pollen, these passing down the tissue of the column to 

 the ovary, where they fertilise the ovules. It is strange, however, 

 that in some orchids, several days, weeks, or months are required 

 for the tubes to perform this journey, although the distance is 

 much shorter than in numbers of other flowering plants. Sachs, 

 too, has remarked that " the embryo remains until the seed is ripe 

 as a small round body, consisting of only a few cells, without any 

 external differentiation into stems, leaves, and root ; this only 

 takes place after germination, and even then sometimes quite 

 imperfectly." To insure the fertilisation of the ovules, a large 

 number of pollen tubes enter the ovary, and occasionally they can 

 be there seen by the naked eye, like a number of fine white hairs. 

 When fertilisation is effected, the flowers at once commence 

 fading, and it is curious to see flowers, that would perhaps have 

 lasted for several weeks, show signs of decay in a few hours after 

 the pollen is placed on the stigma. 



THE THEORY OF ORCHID 

 STRUCTURE. 



A FEW words only need be given upon this, but they will perhaps 

 serve to render the strange formation of orchid flowers more 

 readily understood. Tracing the origin of abnormal structures, 

 or their resemblance to the normally formed organs, is termed 

 Homology, and applying this to the orchids, the following results 

 have been obtained, which are now generally accepted, though 

 many different views had been held previous to Darwin's time. 

 The column of an orchid flower is theoretically regarded as com- 

 posed of four stamens and three pistils, two other stamens being 

 combined with the lip, and thus explaining its occasional three 

 lobed form. The stamens are considered to be in two rings, the 

 uppermost of the outer ring being that usually fertile, and the 

 upper two of the inner ring are those seen in Cypripedium, while 

 the lower two of the outer ring are those united with the lip ; the 

 two outer of the stigmas are united, and the upper one forms the 

 rostellum. Comparisons with the flowers of allied plants, and 

 tracing the bundles of spiral cells from the stem, have formed the 

 foundation of this view. 



