COROLLA. 67 



animal substances. Many flowers exhale sweet odors ; but, ho-wever odors may 

 differ in the sensations which they produce, it is certain that powerful ones have a 

 stupefying, narcotic effect upon the nerves, and that it is dangerous to respire for 

 any great length of time even the most agreeable of them in a concentrated state. 

 b. One important ofhce of tlie corolla, is to secure those delicate and important 

 organs which it incloses, the stamens and pistils, from all external injury, and to 

 favor their development. After the germ is fertihzed by the influence of the pol- 

 len, the corolla fades away, and either falls off or remains withered upon the stalk ; 

 the juices which nourished it then go to the ovary, to assist in its growth, and ena- 

 ble it to become a perfect fruit. Another use of the corolla seems to be, to furnish 

 a resting-place for insects in search of honey. The corolla is supposed by Darwin 

 to answer the same purpose to the stamen and pistils, as the lungs in the animal 

 system ; each petal being furnished with an artery which conveys the vegetable 

 blood to its extremities, exposing it to the light and air under a delicate moist 

 membrane ; this vegetable blood, according to his theory, is then collected and 

 returned in correspondent veins, for the sustenance of the anthers and stigmas, and 

 fur the purpose of secreting honey. After all our inquiries into the uses of the 

 corolla, we are obliged to acknowledge that it appears less important in the econ- 

 omy of vegetation, than many less showy organs. It seems chiefly designed to 

 beautify and enliven creation by the variety and elegance of its forms, the bril- 

 liancy of its coloring, and the sweetness of its perfume. 



75. In many flowers there is an appendage, formerl}^ called 

 tlie nectary (from nectar^ lioney)^ which secretes a peculiar fluid, 

 the honey of the plant. Linnoeus considered the nectary as a 

 separate organ from the corolla ; and every part of the flower 

 which was neither stamen, pistil, calyx, nor corolla, he called a 

 nectary ; but what he called nectaries are at present regarded 

 as modifications of some part of the flower ; in some cases a 

 mere prolongation of the petals, and in others an inner row ol 

 petals or modified stamens adhering to the corolla. With this 

 explanation, we shall use the term nectary as it has been ap- 

 plied by preceding writers. 



a. The term disk is now applied to whatever appendage ap- 

 pears between the stamen and j^istils, formerly called nectaries ; 

 the disk is often formed from the degeneration and transforma- 

 tion of stamens, presenting the appearance of scales, glands, 

 hairs, (fee. Its common form is that of a rhn or scale^ either 

 surrounding the base or appearing at the tip of the ovary ; it 

 sometimes consists of glands or abortive stamens, alternating 

 with the stamens, sometimes at their base, showing a whorl of 

 abortive stamens. 



Sometimes the disk or nectary is a mere cavity, or gland, as in the lily. The 

 crown-imperial exhibits in the claw of each of its petals a nectary of this kind; 

 each one being filled with a sweet liquid, the secretion of the flower. The six 

 nectariferous glands at the base of the corolla are represented at Fig. 82. The 

 petals are supposed to be cut to show the base of the flower. The analogy of 

 petals with stamens is argued from the existence of these glands or cavities, the 

 fluid contained in them being found to be of the same nature as that which is 

 elaborated into pollen. 



In the ranunculus the secreting organ is a production of tlie corolla in the form 



Dangerous if respired for a long time— A. Offices of the corolla — Darwin's theory with respect to the 

 corolla. — 75. Nectary — Its use — a. Nectaries not cousidered as a special organ — a. Disk. 



