NECTAKIES OF THE INVOLUCRE. 31 



EXTERNAL NECTARIES OF THE INVOLUCRE. 



The Guatemalan cotton protected by the keleps has three broadly 

 oval or reniforni pits at the base of the involucre, one at the middle 

 of the base of each of the involiicral leaves." These are larger, deej^er, 

 and more active than the nectaries of any of the Texas varieties as 

 vet observed, though there is very great diversity of size and nectar- 

 secreting activity. In some of the varieties these nectaries are 

 reduced to mere rudiments or are entirely wanting. The depres- 

 sion may be present, but with no secreting tissue. The variety nearest 

 apin'oaching the Guatemal-an cotton in having large and active necta- 

 ries is the Redshank, but the King and other related sorts also have 

 fairly large nectaries. 



The drooping or pendent i)ositiun of the bolls in the Kekchi cotton 

 may be correlated with the special development of these nectaries, as 

 already noted. In the middle of the day the keleps are not veiy 

 active, but the nectaries are sometimes full to overflowing. If the 

 l)olls kept the erect position usual in the varieties cultivated in the 

 United States the nectar would frequently drop off and be lost, but 

 when the fruits hang down the cuplike nectaries are brought upper- 

 most and hold the liquid much longer. 



The evolutionary origin of these nectaries is fairly obvious. The 

 bracts are to be looked upon merely as modified leaves, with nectaries 

 which have increased in size and activity as the leaves have become 

 smaller and more specialized, 



INNER NECTARIES OF THE INVOLUCRE. 



As though to induce the keleps to come inside the involucre and 

 thus more effectually protect the young buds and bolls against the 

 Aveevil, the Guatemalan cotton is also provided with unusually large 

 interior nectaries, alternating in position with those of the outer 

 series and thus placed opposite the edges of the involucral leaves or 

 bracts. These inside nectaries, like the outside ones, are larger and 

 more active than those on most of the cottons cultivated in the 

 Southern States, but the closing of the involucre and the devolopment 

 of the inside nectaries have been carried much farther in the Old 

 World cottons belonging to the species Goxsi/pivm herhacetini. 

 Here the external nectaries are quite Avanting, but the internal ones 

 are enormously larger and heartshaped, and secrete nectar in such 

 quantities that it often flows out in the groove between the adnate 



"I Instances are occasionally found where only two nectaries are developed, 

 but such deficiencies are much less freciuent than lu other varieties of the 

 Upland and Sea Island series. The Rabinal cotton commonly has only two 

 external nectaries. The Old World cottons thus far observed have no nectaries 

 in this position. 



