260 GRADATION OF ORGANS. Chap. IX 



The caudicle, when largely developed and destitute 

 of pollen-grains, is the most striking of the many pecu- 

 liarities presented by the pollinia. In some Neottese, 

 especially in G-oodyera, we see it in a nascent con- 

 dition, projecting just beyond the pollen-mass, with 

 the threads only partially coherent. In the Yandese 

 by tracing the gradation from the ordinary naked 

 condition of the caudicle, through Lycaste in which 

 it is almost naked, through Calanthe, to Gymhidium 

 giganteum, in which it is covered with pollen-grains, it 

 seems probable that its ordinary condition has been 

 arrived at by the modification of a pollinium like 

 that of one of the Epidendreae ; namely, by the abor- 

 tion of the pollen-grains which primordially adhered to 

 separate elastic threads, and afterwards by the cohesion 

 of these threads. 



In the Ophreae we have better evidence than is 

 afforded by gradation, that their long, rigid and 

 naked caudicles have been developed, at least partially, 

 by the abortion of the greater number of the lower 

 pollen-grains and by the cohesion of the elastic threads 

 by which these grains were tied together. I had often 

 observed a cloudy appearance in the middle of the 

 translucent caudicles in certain species ; and on care- 

 fully opening several caudicles of Orchis pyramidalis, 

 i found in their centres, fully half-way down between 

 the packets of pollen and the viscid disc, many pollen- 

 grains (consisting, as usual, of four united grains). 



Aora hns no rostellum to secrete and stigma ; yet I found in one 



the above thick fluid, yet the of thse auricles a distinct caudicle 



pollen-grains are thus united. In (which necessarily had no disc at 



a monstrous specimen of Orchis its extremity), and this caudicle 



pyramidalis the auricles, or nidi- could not possibly have been 



mentary anthers on eacli side of secreted by the rostellum oi 



the proper anther, hnd become stigma. I could advance addi 



partly developed, and they stood tiomil evidence, but it would be 



quile on one side of the robtellum su[)erfluoud. 



