216 Nichols, A morphological study of Juniperus commnuis var. depressa. 



found in Cupressus Goiveniana, as well as those in Juniperus 

 communis, are not without significance. 



Since Juniperus is dioecious the number of pollen tubes found 

 in the ovule depends primarily on the proximity of the staminate 

 and pistülate plants. In the European form Belajeff (1893) and 

 Noren (1907) find four or five pollen tubes in a Single nucellus. 

 A specimen prepared by the writer shows seven pollen tubes, all 

 of which have reached the archegonial region and have formed 

 male cells, so that in this case there are present at the time of 

 fertilization fourteen male nuclei, each of which is capable of 

 uniting with an egg. 



The cytological phenomena which accompany the division of 

 the body cell (or nucleus) to form the male cells (or nuclei) have 

 been carefully studied in only a few Gymnosperms. Webber 

 (1901) finds that in Zamia the spindle is entirely of nuclear origin, 

 and, judging from the figures, a similar intra-nuclear derivation 

 of the spindle would seem to be characteristic of Taxus (Robertson 

 1907) and Ephedra (Land 1907). A peculiar mode of spindle 

 formation is described by Miss Ferguson (1901) in the body 

 nucleus of Pinus, where the spindle is "extra-nuclear and unipolar 

 in origin". According to Miyake (1903 a) the same type of 

 spindle formation occurs in Picea, and it is perhaps characteristic 

 of the Äbieteae. In none of the Cupresseae has this phase been 

 fully worked out. Thus far the most complete observations are 

 those of Coker (1903b), who establishes the fact that in Taxo- 

 dium the spindle fibers are of nuclear origin. In J. communis 

 Sludsky (1905, fig. 2) figures in the anaphase of this division a 

 sharply bipolar spindle, the poles of which are situated near the 

 periphery of the cell. Noren (1907) describes a condition seen 

 shortly before the orientation of the chromosomes at the equator, 

 but finds no indications of spindle fibers. An unsuccessful effort 

 was made by the writer to secure a complete series of the various 

 stages of spindle formation in var. depressa, but several interesting 

 phases of this division were found which prove that, even if the 

 spindle is not intra-nuclear throughout its history, as Sludsky's 

 observations would indicate, it at least originates entirely within 

 the nucleus. 



As the body cell approaches division, it usually loses its 

 spherical shape and becomes ovoid. Up to this time the nucleus 

 has exhibited no features of especial interest. It possesses a large 

 nucleolus, which is frequently vacuolate, and a coarse, anastomosing 

 reticulum in which no düferentiation into chromatin and linin can 

 be made out. The reticulum now resolves itself into a slender, 

 uniformly distributed spirem, which at first, in contrast to the con- 

 ditions described in the pollen mother cell nuclei, shows beautifully 

 a distinction between linin and chromatin very similar to that 

 described by Allen (1905) in the pollen mother cells of lAlium 

 canadense (fig. 55). The chromatin granules are very clearly 

 arranged in pairs and are distributed at fairly regulär intervals 

 along the lighter staining band of linin. In addition to the chro- 



