lOO MARGARET C. FERGUSON 



developed egg-nucleus in any of the species of pines which I 

 have studied. 



During the growth and downward movement of the egg- 

 nucleus, it never presents, in Pimis Strohiis^ a definite network, 

 such as is observed in the nucleus of the ordinary resting cell ; 

 but it is characterized at a very early date by an open, inter- 

 rupted reticulum, on which are arranged irregular granules of 

 various sizes. This meshwork may be extremely delicate ; it 

 may assume a heavy appearance ; or it may become very much 

 interrupted and broken, many detached portions lying loose within 

 the nuclear cavity (figs. 196, plate XVII, to 205, plate XVIII). 

 The egg-nucleus of Pinus cmstriaca and P. montana var. unci- 

 nata^ may frequently show from an early date a beautifully regu- 

 lar reticulum (fig. 269, plate XXIV). Nucleoli have rarely been 

 observed in this nucleus in Piniis Strobus during the first stages of 

 its development (figs. 196, 199 and 200-201) ; but in Pintis aiis- 

 triaca they occasionally arise very early (fig. 195). When the 

 nucleus has attained considerable size, small, nucleolus-like 

 bodies, containing a single central vacuole, appear in connection 

 with the nuclear net ; and at the same time a slightly larger nu- 

 cleolus is observed in the lower part of the nucleus, usually in 

 connection with its membrane (fig. 202). As the nucleus con- 

 tinues to grow, this nucleolus also increases in size, gradually 

 becoming large and very vacuolate (figs. 203-205). 



When the egg-nucleus reaches maturity, it has attained huge 

 dimensions, and its outline, depending on the form of the egg, 

 is spherical or elliptical. The nucleolus, if demonstrable, is 

 always found in the lower part of the nucleus ; and there are 

 usually several smaller bodies, designated in this paper as sec- 

 ondary nucleoli, scattered throughout the nucleus (fig. 205). 

 These secondary nucleoli are invariabl}'^ found in connection 

 with the reticulum, but, as Montgomery ('98) believed regarding 

 apparently similar structures, they are probably caught in, not 

 vitally united to it. They may be present in great abundance, 

 or they may be entirely absent from the nucleus. The reticu- 

 lum, on which the chromatic substance is disposed, presents 

 numerous aspects, as already indicated in the description of this 

 nucleus during its period of growth. Under ver}' high magni- 



