OBJECTIONS TO THE THEORY 331 



one alone of the most striking peculiarities of the 

 flowers of orchids; namely, their pollinia. A pollinium 

 when highly developed consists of a mass of pollen- 

 grains, affixed to an elastic foot-stalk or caudicle, and 

 this to a little mass of extremely viscid matter. The 

 pollinia are by this means transported by insects from 

 one flower to the stigma of another. In some orchids 

 there is no caudicle to the pollen-masses, and the grains 

 are merely tied together by fine threads; but as these are 

 not confined to orchids, they need not here be considered; 

 yet I may mention that at the base of the orchidaceous 

 series, in Cypripedium, we can see how the threads were 

 probably first developed. In other orchids the threads 

 cohere at one end of the pollen-masses; and this forms 

 the first or nascent trace of a caudicle. That this is the 

 origin of the caudicle, even when of considerable length 

 and highly developed, we have good evidence in the 

 aborted pollen-grains which can sometimes be detected 

 imbedded within the central and solid parts. 



With respect to the second chief peculiarity, namely, 



ithe little mass of viscid matter attached to the end of the 



[Caudicle, a long series of gradations can be specified, 



3ach of plain service to the plant. In most flowers 



3elonging to other orders the stigma secretes a little 



;riscid matter. Now in certain orchids similar viscid 



patter is secreted, but in much larger quantities by one 



lone of the three stigmas; and this stigma, perhaps in 



onsequence of the copious secretion, is rendered sterile. 



Vhen an insect visits a flower of this kind, it rubs off 



ome of the viscid matter and thus at the same time 



rags away some of the pollen-grains. From this simple 



ndition, which differs but little from that of a multitude 



