224 Nichols, A rnorphological study of Jumperus communis var. depressa. 



the central cell begins to show the peculiar aster-like structures 

 which Noren (1908 ) terms "Strahlungscentren", and for which the 

 writer suggests the term Asteroid. Granulär areas appear which 

 occupy definite positions in the cell, and from these the cytoplasm 

 radiates in all directions. These kinoplasmic radiations, as shown 

 in figs. 80 — 85, present the appearance of granulär übers, and the 

 whole structure assumes the form of an immense aster. One of 

 these asteroids is invariably situated in close proximity to the 

 nucleus, and a second one may frequently be seen directly below 

 this, while one or more are present in the lower part of the cell 

 (figs. 91, 95). They are most prominent during the division of the 

 central cell nucleus, but the lower ones at any rate are still visible 

 in the egg cell shortly betöre fertilization. The significance of 

 the asteroids, especially of those in the lower portion of the arche- 

 gonium, is not clear. Coker (1903b) suggests that the latter 

 regulate the entrance of nutritive materials from the jacket cells, 

 while Noren (1907) regards them as attraction centers, since, as 

 the writer's investigations also show, granules of the cytoplasm 

 are drawn toward them and accumulate at their centers (see 

 Noren 1907, fig. 10). It may be worthy of note that the first 

 appearance of the protein vacuoles follows shortly after the Or- 

 ganization of the asteroids. Concerning the probable function of 

 the upper asteroid mention will be made presently. Structures 

 similar to these have been observed by Coker (1903b, 1902) in 

 Taxodium and Podocarpus, by Land (1902) in Thuja, and by 

 Lawson (1907 a) in Cephalotaxus. In several other Gymnosperms, 

 viz., Gycas (Ikeno 1898), Dioon (Chambe riain 1906), Pinus 

 (Blackman 1898, Chamberlain 1899, Ferguson 1904), Tsuga 

 (Murrill 1900), Picea and Äbies (Miyake 1903a, 1903b), kino- 

 plasmic radiations of a more or less pronounced character have 

 been either described or figured in connection with the di- 

 vision of the central cell nucleus or the development of the egg, 

 but they are much less conspicuous than the structures found in 

 Juniperus, where they form one of the most striking features of 

 the archegonium. 



The occurrence of "Hofmeisters Körperchen", or protein 

 vacuoles, in the archegonium of J. communis has already been de- 

 monstrated by Noren (1907, fig. 65). In var. depressa they appear 

 shortly before the division of the central cell nucleus and are seen 

 to best advantage in the lower part of the egg cell just previous 

 to fertilization. Immediately after the fusion of the male and 

 female nuclei the protein vacuoles begin to disappear and at no 

 time are they as conspicuous as in the Abieteae. Their significance 

 has been the cause of considerable controversy, and for a füll 

 review of the literature the reader is referred to the excellent paper 

 of Stopes and Fujii (1906). These authors suggest that the 

 protein vacuoles "may be digestive vacuoles comparable in origin 

 and function with the digestive vacuoles of the lower organisms". 

 Whatever their function, it is now generally agreed that they arise 

 within the central cell and are in some way concerned with the 

 nutrition of the egg. 



