480 Woolery.—Meiotic Divisions in the Microspore 
2. There is no lateral pairing of the chromatin threads during this or 
the synaptic stage. Neither does the chromatin content consist of a number 
of chromatin threads which equals the diploid number of chromosomes for 
the species. 
3. Synapsis is a stage which is characterized by a very general con¬ 
traction of the nuclear contents into a tight ball, usually lying at one side 
of the cavity, and an increase in the size of the nuclear cavity. 
4. The contents of the nucleus are often connected with the nuclear 
membrane by fine strands. 
5. The mass of chromatin threads untangles, and a continuous spireme 
of uniform diameter is evenly distributed throughout the nuclear cavity. 
Connexions between the chromatin thread and the nuclear membrane still 
persist. 
6 . Immediately after this state of the evenly distributed spireme 
follows a second contraction or central entangling of the spireme with loops 
radiating from the centre to the periphery. Longitudinal splits may be 
seen in the thread at this time. 
7. Cross-segmentation of the chromatin thread takes place either at the 
centre or near the periphery of the tangle, and a lateral approximation of 
the limbs of loops or of separate portions of chromatin thread takes place 
to form the bivalent chromosomes. 
8. Fibres appear around the nucleus, the membrane breaks down, the 
characteristic bipolar spindle is finally formed, and the bivalent chromosomes 
are arranged in a plate at the equator of the spindle. 
I wish to express my gratitude to Prof. D. M. Mottier for his most 
helpful suggestions and criticisms during the preparation of this paper. 
Indiana University. 
Literature cited. 
Farmer, J. B., and Moore, J. E. S. (’ 05 ): On the Maiotic Phase (Reduction-division) in Animals 
and Plants. Quarterly Journal of Microscopical Science, vol. xlviii, 1905, Part IV. 
Farmer, J. JB. (’ 07 ) : The Structural Constituents of the Nucleus and their relation to the Organization 
of the Individual. Croonian Lecture, Proc. Roy. Soc. London, Series B, vol. lxxix, 1907, 
P. 534 - 
-(T 2 ) : Nuclear Osmosis and its assumed^relation to Nuclear Division. The New 
Phytologist, vol. xi, 1912, pp. 139-44. 
-—-(T 3 ) : Nuclear Osmosis and Meiosis. The New Phytologist, vol. xii, 1913, 
pp. 22-8. 
Farmer, J. B., and Digby, L. (T 3 ): On Dimensions of Chromosomes considered in relation to 
Phylogeny. Philosophical Transactions of Royal Society of London, Series B, vol. ccv, 
1913, pp. 1-25. . 
Lawson, A. Anstruther (’ 11 a): The Phase of the Nucleus known as Synapsis. Transactions 
Royal Society of Edinburgh, vol. xlvii, Part III, 1911, pp. 591-604. 
