Elementary biology; an introduction to Elementary biology; an introduction to the science of life elementarybiolog00grue Year: 1924 PROTECTIVE ARMORS 349 It seems likely that in many plants the hairs are really related to the moisture. The absence of moisture, or, rather, a shortage of Cortex Shaft ifedtiUa Horny ^M: layer 'i^'^-^Dermis ' \haceoui> gland Papilla with blood vessels b -~~1 6 = 3 Fig. 164. Hair of mammals Branches of f^haft formbuj barbules Horny layer r, human hair follicle, showing mode of growth (the dead shaft is pushed forward by the new growth about the papilla); 2,
Elementary biology; an introduction to Elementary biology; an introduction to the science of life elementarybiolog00grue Year: 1924 PROTECTIVE ARMORS 349 It seems likely that in many plants the hairs are really related to the moisture. The absence of moisture, or, rather, a shortage of Cortex Shaft ifedtiUa Horny ^M: layer 'i^'^-^Dermis ' \haceoui> gland Papilla with blood vessels b -~~1 6 = 3 Fig. 164. Hair of mammals Branches of f^haft formbuj barbules Horny layer r, human hair follicle, showing mode of growth (the dead shaft is pushed forward by the new growth about the papilla); 2, hair of horse ; s, hair of mouse ; 4, hair of marmot. a, base of hair ; ^, tip; c, more highly magnified portion of shaft moisture, is known to bring about the production of hairs in species of plants that ordinarily do not produce hairs when water is abundant. Hairs are also likely ^,,^^Shcath to protect many plants against extremely high or low temperature. The hairs familiar to us in common animals and on our own skin are much more complex in structure than are plant hairs (Fig. 164). The feather of the bird may be considered as a highly complex hair. In the manner of growth the feather resembles the hair of mammals very much, but in its structure it is of course very
Size: 1112px × 1798px
Photo credit: © Bookworm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
