. Morphology of gymnosperms. Gymnosperms; Plant morphology. CONIFERALES (PINACEAE) 267 maturation changes (51, 126). A similar case was reported for Ginkgo by Tkeno. Such a nucleus appears to be ready for fertiliza- tion. In Abies balsamea (79a) the ventral canal nucleus usually enlarges somewhat and persists until fertilization. There are also cases in which the wall separating such a ventral nucleus from the egg has been observed to disappear, leaving two simi- lar nuclei free in the cyto- plasm of the egg (51); and such equal nuclei have been observed in contact (fig. 298), as if fusing' (2
. Morphology of gymnosperms. Gymnosperms; Plant morphology. CONIFERALES (PINACEAE) 267 maturation changes (51, 126). A similar case was reported for Ginkgo by Tkeno. Such a nucleus appears to be ready for fertiliza- tion. In Abies balsamea (79a) the ventral canal nucleus usually enlarges somewhat and persists until fertilization. There are also cases in which the wall separating such a ventral nucleus from the egg has been observed to disappear, leaving two simi- lar nuclei free in the cyto- plasm of the egg (51); and such equal nuclei have been observed in contact (fig. 298), as if fusing' (23, 44). It seems reasonable to infer that the ventral canal cell is an abortive egg, which is occasionally organized as an egg, and which in that condition may be fertilized (72), or may fuse with the egg nucleus. The ventral nucleus has also been ob- served to divide (after the fertilization of the egg), either by amitosis (76) or mitosis (72). The account of the archegonium given above applies in general outline. Fig. 2g8.—Pinus Laricio: conjugation of two nuclei which were described as male (to) and female (/), but which are doubtless the nuclei of the egg and ventral canal cell, as in fig. 297; both nuclei are in an early spirem stage; it is interesting to note that the first record of fertilization in gymnosperms (Picea, reported by Strasburger 22) was very probably a case of this kind; Xsoo.—After Coulter (44). to all the Pinaceae, but there are differences, among the tribes that must be considered. Among the Abietineae the number of archegonia ranges from one to seven, with two to five as the usual range, the smallest among Pinaceae. The number of neck cells may be said to average about eight, arranged in two tiers, with four cells in each tier; but there. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original
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