47 2 Woolery.—Meiotic Divisions in the Microspore 
As an aid in determining the true form and arrangement of chromatin 
in the second contraction, and segmented stages, nuclei were reconstructed 
in plastina, in order to facilitate the interpretation of the individual chromo¬ 
somes. 
The Smilacina which Lawson (T 1 a and T 2 ) used was probably 
Maianthemum Convallaria , Roth, as described in ‘British Flora’, fifth edition 
(1887), Bentham and Hooker, or the same plant as described under Unifolium 
canadense (Desf.), Green, or Smilacina bifolia , Desf., in Britton and Brown, 
second edition (1913). The plant used for this study is Smilacina racemosa 
(L.), Desf., as described in Gray’s Manual, seventh edition (1908), or the 
same plant as is described as Vagner a racemosa (L.), Morung, in Britton and 
Brown, second edition (1913). 
Statement of the Proelem. 
An attempt has been made in this investigation to make a very careful 
study of some of the stages in the meiotic divisions of the pollen mother-cells 
as found in Smilacina racemosa (L.), Desf. There has been much contro¬ 
versy for several years about some phases of cell activity, and, as Farmer (T2) 
says, ‘ there is still room for more light ’. 
The questions of the identity of the chromosomes throughout meiosis 
and of the behaviour of chromatin threads previous to and during synapsis 
have been much discussed in cytological literature, and there is still much 
diversity of opinion in regard to these questions. Among the other ques¬ 
tions with which this paper deals are : the character of the synaptic ball, its 
position and relation to the size of the nuclear cavity, the nature of the 
chromatin thread after synapsis, during the spireme stage, and in the second 
contraction, the manner in which the thread segments, and the formation of 
the bivalent chromosomes. 
Resting Stage . During the so-called resting stage the chromatin 
granules are arranged irregularly on fine linin threads throughout the 
nuclear cavity, giving the appearance of a network. The granules are more 
or less irregular in size, shape, and form. The appearance of a network is, 
no doubt, partly due to the overlacing of threads, as suggested by Lawson 
(’ll a), but there seem to be more crossed threads than there would be were 
this entirely the case. The fact that some portions of the fine linin thread 
to just the intensity wanted in the finished preparation, the slide should be rinsed hurriedly with 
absolute alcohol and then covered with the clove oil violet. The violet should be allowed to act 
20 minutes to 3 hours, although in some cases staining for 6 hours has given good results. It is 
then washed off with benzole or xylol and replaced with clove oil orange G. If staining of 
walls is not wanted, final differentiation may be secured by using pure clove oil after 10 to 15 
minutes’ use of the orange G solution. It has been found well to remove the clove oil orange G 
completely with flowing benzole or xylol and to mount the specimen from that medium. It is 
essential that no alcohol be allowed to come in contact with the sections after the use of the clove 
oil violet, 
