Studies in Heredity as Illustrated by the Trichomes of Species and Hybrids of Juglans, Oenothera, Papaver, and Solanum (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1909 Excerpt: ...is 13.6 / (table 13). Taiii.k 13.-Measurements on short secreting trichomes, Juglans regia. GENERAL COMPARISON OF THE LEAVES AND THE TRICHOMES IN PURE SPECIES OF JUGLANS. In leaf-characters the pure species of Juglans are fairly sharply separated from one another. For example, in number of leaflets regia has less than one-half those of either of the other species, and the range in number of leaflets in californica is considerably less than the range in nigra. In form of the leaflets the species are not so sharply distinguishable. The leafcharacter, however, is a good one to observe in the hybrids between these species. Although somewhat difficult in all cases to speak with certainty, with a single exception it appears that all of the types of trichomes occurring in any one species may be found in all, and, further, that the leading points in structure and development are the same wherever the trichome is to be found. Four types of trichomes occur in calif ornica and regia and an additional type in nigra. Of these, one form is unicellular and lifeless, the others are multicellular and glandular. So far as could be determined from the material at hand, each type of multicellular trichome appears to have its peculiar manner of development, as suggested above, to which it adheres with great consistency. After the trichome rudiment has been formed the divisions of the short secreting trichome were, first, a crosswall separating the head from the stalk; second, a longitudinal wall in the head; third, a cross-wall in the stalk; and fourth and fifth, two longitudinal divisions of the head. The long secreting trichome experiences the same sequence of cell-divisions and to them adds 2 in the stalk. The sequence of division of the disk-shaped trichome is the same for ...