50 2 The Ohio Naturalist. [Vol. IX, No. 7, 



ally contains several micronucleoli, and a network of chromatin 

 matter (Fig. 25). The pellucid matter which surrounds the 

 generative nucleus contains many minute granules and is prob- 

 ably the cytoplasm of the new cell. Convallaria agrees with most 

 of the other Monocotyledons in the early separation of its gen- 

 erative cell. No sperm-nuclei could be found, and their forma- 

 tion doubtless takes place during the formation of the pollen- 

 tube, and is, therefore, a part of fertilization, as it is in most of 

 the Monocotyledons. 



SUMMARY. 



1. The continuous spireme up to and through synapsis is a 

 single row of chromatin granules on a linin thread. 



2. The chromatin granules seem to show a temporary 

 division shortly after synapsis. 



3. The spireme shortens and thickens, and breaks up into 

 sixteen chromosomes. 



4. The first division of the chromosomes in the microsporo- 

 cyte is transverse, and, therefore, qualitative. 



5. The homologous daughter chromosomes show marked 

 similarity in size and shape. 



6. The daughter chromosomes of the first division seem to 

 represent the chromosomes of the second. 



7. The second nuclear division is longitudinal, and therefore, 

 equational. 



8. The spore-tetrad breaks up into four incipient pollen- 

 cells, in each of which a generative cell forms, quite a while 

 before the flower opens. 



9. The nucleolus fragments and passes into the cytoplasm just 

 before or during the prophases of the two reduction divisions. 



10. The nuclear membrane disappears during late prophase, 

 is absent during metaphase and early telophase, is present in late 

 telophase and remains during subsequent stages. 



11. The chromosomes of the generative cells are thicker, but 

 not longer than the chromosomes of the sporophyte cells. 



12. The homologous daughter chromosomes of the second 

 division also show a marked similarity in size and shape. 



University of Cincinnati, Feb., 1909. 



LITERATURE CITED. 



McClung, C. E., '05. The Chromosome Complex of Orthop- 

 teran Spermatocytes. Biol. Bull., No. 5. 



Strasburger, E., '88. Ueber Kerntheilung und Zelltheilung 

 im Pflanzenreich. Hist. Beitr. I. Jena, 1888. 



Weigand, K. M., '99. The Development of the Microspor- 

 angium and Microspores in Convallaria and Potamogeton. Bot. 

 Gaz. 28. 



'00. The Development of the Embryo-sac in Some 



Monocotyledonous Plants. Idem 30. 



