498 The Ohio Naturalist. [Vol. IX, No. 7, 



MATERIAL AND METHODS. 



Neubert's "Multibell" brand of German Lily-of-the-Valley 

 pips were "forced" in moist sand, at the temperature of about 

 20 C, in a green-house, in subdued Hght. When the sprouting 

 pips were of various lengths stamens were isolated from the 

 flower buds. Pips two to four centimeters in length contained 

 all the stages desired. After killing and fixing the anthers in a 

 chrom-acetic acid solution* they were washed in tap-water, 

 passed through the series of alcohols, and preserved in 85% 

 alcohol. Paraffin (51° C.) sections (3-lOu), stained on the slide, 

 cleared in xvlol, and mounted in balsam, were used for study. 

 Longitudinal and transverse sections of anthers were made. As 

 stains, Heidenhain's iron-alum-haematoxylin with Orange-G, 

 and Delafield's haematoxylin with safranin gave good results. 

 Drawings and observations are based on slides stained chiefly 

 with the former combination. The pollen mother-cells near the 

 apex of the anther are slightly more advanced than those nearer 

 the filament. 



OBSERVATIONS. 



The nucleus enters a state of rest at the conclusion of the last 

 archesporial division of the sporophyte tissue (Fig. 1). This is 

 of short duration, however, and the chromatin matter soon 

 becomes transformed into a number of fine, delicate threads in 

 the form of a network (Fig. 2) . The nucleolus is visible from the 

 beginning, and it, as the cell becomes larger, behaves peculiarly 

 (Figs. 1-8), in that it becomes larger, less chromatic, and shows a 

 clear, vacuole-like area near its center. Occasionally it frag- 

 ments into micronucleoli. With an increasing volume of the 

 cells the chromatin matter of the nucleus becomes more con- 

 spicuously granular, and the linin appears to contract. There 

 seems to be a reciprocal loss of chromatic substance from the 

 nucleolus (Figs. 6, 7, 8). The clear area in the nucleolus makes 

 it resemble in appearance an erythrocyte of man (Fig. 6a). 

 Occasionally two such clear areas are noticeable in the nucleolus 

 (Fig. 8). The cell increases in volume, the spirem continues to 

 contract, and the continuity of the thread becomes more and 

 more apparent (Figs. 3, 3a, 4, 5a). 



From now until the apparent climax of the process which 

 ends in synapsis, the contraction of the spireme thread is more 

 rapid, and the network becomes more twisted. The linin is at 

 all times of smaller diameter than the chromatin granules (Figs. 

 3a, 5a). The continuity of the twisted spireme thread becomes 

 very apparent, and the thread becomes entirely separated from 



* Chrom-acetic acid solution: Chromic acid 0.3g., glacial acetic acid 

 O.Tcc, water 99cc. 



