90 GENERAL l^EVIEW OP THE 0RCHI1)E.'^:. 



temperature iluring the Mlmh^ year, tliewe periods are not only shorter 

 but more uniform among different genera. The progress of development 

 during the earliest stages of growth is also exceedingly difficult to trace 

 without the aid of the microscope on account of the minuteness of 

 the seed and the indistinctness of the first indications of growth. The 

 first development of the cotyledon from the spindle-shaped seed discernible 

 by the naked eye has the appearance of a thalloid bodj' of irregular 

 form but nearly always of the same contour in the same genus, and 

 of a bright green colour indicating that the cells of the epidermis and 

 underlying tissue are rich in chlorophyll. In Cattleya this thalloid body 

 is at first a thickened disk, with an out-growth on the upper side which 

 ultimately develops into the first ])air of scale-like leaves; in Dendrobium 

 it has a fusiform shape with a sharply pointed out-growth at one end, 

 the rudiment of the first leaf ; in Phalsenopsis it is prismatic with 

 the angles much rounded ; and in Cypripedium it is nearly flask-shaped. 

 The subsequent development will be better understood by reference to 

 the figures than from verbal description. 



The period from the germination of the seed to the first flowering of 



the plant varies more in some genera than in others ; thus, in Cattleya 



and Lselia (which are as regards hybridisation one genus, excluding 



some Mexican species referred to Lselia) the shortest recorded period is 



' six years. Lcdia x caloglossa raised by Dominy from Cattleya labiata 



and Lcelia crispa was nineteen years before it flowered, but this is 



undoubtedly an extreme case. The periods in ten recorded instances 



ranged from seven to ten years, while those of some of the older 



hybrids were a little longer. In Dendrobium the period is usually 



four or five years ; in Phalaenopsis from four to six years ; in 



Cypripedium from four to six years with a few cases of shorter 



duration, but five years is recorded for more crosses than any other 



period. The shortest periods occur in the Calanthes of the Vbstit^ 



section ; these usually flower from three to four years from the seed. 



Seedling Epidendra and Masdevallias flower in about four years. It 



is a remarkable fact that the period of terrestrial orchids from the 



germination of the seed to the first flowering of the plant, like the 



fertilisation of their ovules is much shorter than in the epiphytal 



species ; thus Disa x Veitchii raised by Seden from D. grancUflora 



and D. racemosa flowered in twenty-one months from the sowing of 



the seed ; and with D. x Premier raised by Mr. Watson at Kew from 



D. X Veitchii and D. tripetaloides the period was still shorter. 



The fact that most orchid flowers if fertilised at all must, in the 



wild state, be fertilised by insect agency being once recognised, it 



follows that where two allied species grow together or in close 



proximity to each other, the pollen of the one is liable to be 



deposited on the stigma of the other, and crosses may thence be 



