386 Bibliographical Notices. 



this movement and interval of time (which would allow the insect to 

 fly to another flower), it will be seen that if the pencil [or proboscis] 

 be inserted into the nectary, the thick end of the pollinium will 

 exactly strike the stigmatic surface." 



That things go on in the way just described was demonstrated 

 experimentally by Mr. Darwin by the simple expedient of thrusting 

 the point of a pencil or some similar object into the orifice of the 

 nectary, when one or both of the pollinia are certain to be removed, 

 and the subsequent change of position for enabling the pollen to 

 reach the viscid stigmatic surfaces of another flower may easily be 

 observed. The occurrence of the same phenomena by the inter- 

 vention of moths and other sucking insects is proved by the frequent 

 occurrence of pollinia adhering to their proboscides. Mr. Darwin 

 gives a list of twenty-three species of Lepidoptera on which pollinia 

 of Orchis pyramidalis have been met with ; he figures the head of 

 a specimen of Acontia luctuosa with seven pairs of pollinia attached 

 to its proboscis, and mentions one of a Caradrina which bore no 

 fewer than eleven pairs of these pollen-masses. 



As the general principle on which the fertilization of Orchids de- 

 pends is nearly the same throughout, although the different means 

 by which its effectuation is ensured present many beautiful and won- 

 derful contrivances, the extract above given may suffice for our pre- 

 sent purpose ; the reader will, however, find the details given by 

 Mr. Darwin on all points connected with the impregnation of these 

 plants most interesting. We may, however, trespass a little further 

 upon his time in order to advert to one case which appears to us 

 particularly remarkable. 



In Catasetum, one species of which is now known to be the 

 male form belonging to a female plant placed by botanists in quite a 

 different genus, the two pollinia are affixed to a common, broad and 

 strong pedicle bearing at its lower end a single disk coated with 

 viscid matter. The latter, however, is so turned into the interior of 

 the column that -no insect can by any possibility get at it, and indeed 

 there seems to be nothing to induce even the most inquisitive insect 

 to push his proboscis into the vicinity of the disk. How, then, is it 

 to be set free ? Mr. Darwin describes a pair of long, stiff and taper- 

 ing organs, which he calls antennae, projecting from the sides of the 

 column close to the insertion of the pedicle of the pollinia ; these 

 hang down over the pouch-like labellum, in such a position that an 

 insect moving about upon the latter can hardly fail to touch them. 

 The slight irritation thus caused appears to produce some singular 

 effect upon the tissues about the base of the pollinia : the membranes 

 retaining the common pedicle in its position are ruptured; the heavy 

 viscid disk is set free, and is drawn forth by the sudden extension of 

 the previously curved pedicle, which straightens itself with such 

 force as to jerk the pollinia out of their cells and project the whole 

 organ to a distance often of two or three feet, the disk with its viscid 

 coat being always carried foremost, ready to adhere to any object. 



Mr. Darwin sums up, as follows, the phenomena presented by the 

 genus including Catasetum, Monachanthus, and Myanthus of bota- 



