IMMUNITY OF VERY YOUNG BOI.LS. 58 



that the Eg-yptiau cotton, the bolls of which are excessively oily, is 

 (111 this accoiiiii ininmiic from the hollworin." The oil contained in 

 the glands has a deep-brown color, a sticky, molasses-like consistence, 

 a disagreeable, pungent odor, and a sharp, resinous taste, suggesting 

 turpentine or Canada balsam. 



The development of the oil glands seems to be especially great in 

 the Egyptian variety known as Mit xVfifi, and the glands are more 

 superficial. By slight pressure, or by drawing the nail across the sur- 

 face, the oily liquid is freely obtained. Most of the Upland varieties 

 have the oil glands much more scattering and deep set than the Egyp- 

 tian sorts, and it is not possible to squeeze the resin out of them in 

 any such manner. 



On Redshank and other Upland types the resin glands are marked 

 by slight superficial depressions, but a cross section shows them to be 

 well below the surface, with several layers of chlorophyll-bearing 

 cells betW'een. On the Egyptian sorts the glands are also set in de- 

 pressions, but the gland itself is very close to the surface, and makes 

 the bottom of the depression again convex, the superficial layer of 

 cells being very thin. It seems to break spontaneously in some in- 

 stances; at least there are frequently small spots of hardened resin, 

 and very slight pressure brings out the dark, gummy fluid. The 

 fingers receive a permanent brownish stain, which with the acrid, 

 biting sensation experienced when the liquid is applied to the tongue, 

 increases the probability that substances of a definitely protective 

 character are present. It is w^ell known that many of the aromatic 

 oils are for some reason highly distasteful or even fatal to many 

 insects. 



The Sea Island and Kidney cottons have the oil glands conspicu- 

 ously developed, like the P]gyptian varieties, but the Old World 

 cotton {Gassy piion herhacevm) is in this, as well as in other respects, 

 more nearly related to the American ITjjland cotton {Gossyphmi hir- 

 siiti/m). The Aidin (Asia Minor) variety of Go.sst/ph/m herhacevm 

 has the oil glands rather small and deep set, with the superficial pits 

 rather shallow, more so than the Ceylon or Korean types. 



Even the petals of the Guatemalan Kidney cotton found at Trece 

 Aguas '' contained oil glands. The color of the petals was a uniform 

 pale yellow, without purple spots on the inside, but in the upper 



<' Qualntaiice, A. L., and Brues, C. T., 1905. The Cotton Bolhvorm, Bui. 50, 

 Hui-eau of Entomology, U. S. Department of Agriculture, p. 71. 



''The Kidney cotton at Trece Aguas is called iHiiyJ. and seems to have little or 

 no relation in the minds of the Indians with the dwarf Upland cotton, which is 

 called nol{. In the Secanquim district, only a few miles away, this name paiyi 

 (pronounced like the English words pie ye) is not recognized. Kidney cotton, 

 though ai^parently not now i^lanted by the Indians, is not entirely unknown to 

 them. They call it simply che nok, or tree cotton. 



