37G REYTEWS. 



to a greater than usual twist of the ovary, and the upper sepal and 

 petal are reflexed instead of protecting the flower. The pollen- 

 masses are almost wholly exposed, and so placed that an insect 

 must withdraw tliem on visiting the flower, and carry them off" lying 

 parallel to its proboscis, and in the proper position for being applied 

 to the stigmatic cavity of the next flower visited. 



Listera ovata. The rostellum is here exceedingly curious, being 

 divided internally into loculi, a structure found in no other Orchid 

 but Neottia. It is exquisitely sensitive, rupturing suddenly with a 

 touch of the finest human hair, and ejecting a ball of viscid matter 

 at its apex. The pollinia, wliich lie free and are very friable, have 

 their bases so close to the apex of the rostellum, as to be invariably 

 entangled in the expelled viscid mass. The long lip presents a lon- 

 gitudinal nectarial ridge. Insects visit this, crawl upwards, touch 

 the apex of the rostellum, when the viscid matter shoots out, carry- 

 ing the pollen masses by tlieir entangled lower ends, and glueing 

 them to the insect's head The insect visits other flowers, and masses 

 of the friable pollen are left on their stigmatic surfaces. 



Listera cordata and Neottia nidus-avis present essentially the 

 same structure and method of fertilization as L. ovata. 



To complete this extremely brief and incomplete account of the 



phenomena in British Orchids we should by right aUude to Cypri- 



pedium, of which genus however only exotic species were examined. 



This genus, as is well known, differs from all other Orchids in having 



three confluent stigmata (hence no rosteUum), the anther of other 



Orchids represented by a shield-like body, two fertile anthers, and in 



the pollen grains being glutinous. Fertilization seems here to take 



place by insects visiting the flower to extract the sweet fluid from 



the glandular hairs within the labellum ; to effect this they insert 



their proboscis into a narrow chink which leads to the anthers, the 



sticky grains of which attach themselves to their proboscis, and are 



■ conveyed to other flowers. Oypripedium is thus the only genus in 



which the pollen grains attach themselves not only to the insect's 



proboscis but to the stigmatic surface, which is not viscid. 



We have preferred thus giving a rather extended resume of Mr. 

 Darwin's observations on British Orchids to reviewing the very ex- 

 tensive and intricate chapters devoted to foreign Orchids, tlie homo- 

 logies of Orchid flowers, and general considerations ; both because they 

 may be repeated by any observer and extended by many, and because 

 this procedure of ours gives a better idea of the completeness of the 

 work than a more sporadic selection of his observations and experi- 

 ments, results and conclusions, could have. Those other chapters are 

 however by far the more interesting and important, and to them we 

 shall at some future time recvu", if opportunity offer. It remains to 

 add that the work is copiovisly illustrated with most useful and in 

 general very clear woodcuts, which would, however, have been greatly 

 increased in value had the insects been introduced, in position, on 

 the flowers. 



