The Ohio ^iSl^aturalist, 



PUBLISHED BY 



The Biological Club of the Ohio State Uni'versity. 



Volume IX. MAY. 1909. No. 7. 



TABLE OF CONTENTS. 



Sauer — Xuclear Divisions in tlie Pollen Mothei' Cells of Convalhiria Majalis L 497 



SCHAFFNEE— Chromosome Difference in Ascaris megalocephala 506 



Paekeii— The Catalpa Leaf Spot 509 



Geiggs— A Note ou Amitosis by Con.striction in Synehytrium 513 



FOERSTE— The Bedford Fauna at Indian Fields and Irvine, Kentudvy 515 



McCeav— Meeting of the Biological Clnb 521 



NUCLEAR DIVISIONS IN THE POLLEN MOTHER-CELLS OF 

 CONVALLARIA MAJALIS L. 



Louis W. Sauer. 



The significance which recent investigators have read into the 

 two maturation divisions, as well as the peculiar behavior of the 

 chromatic -substance during and after synapsis, make the 

 chromosome the cynosure of all the problems in heredity. 



Although the Liliaceae have served as a classical group of 

 angiosperms for this kind of work in botanical research, only 

 twice have their closest allies, the Convallariaceae, received 

 attention. Strasburger ('88) in a very general way, refers to the 

 chromosomes of Convallaria, and Weigand ('99, '00) takes up the 

 development of the microsporangium, and of the embryo sac of 

 Convallaria, but little emphasis is laid on the nuclear divisions in 

 the pollen mother-cells. Weigand holds that the reduced 

 number of chromosomes is eighteen, that he could not determine 

 the plane of the first nuclear division of the mother cell, and that 

 the plane of the second division appears to be transverse. He 

 further states that at several instances the chromatin behaves 

 peculiarly, and that the generative cell of the pollen grain is cut 

 off shortly before the flower opens. 



The present writer undertook a careful study of the nuclear 

 phenomena of the pollen mother-cells of Convallaria majalis L, 

 with the hope of making further contribution towards the soKi- 

 tion of the problem of heredity and the chromosome. With 

 none of the above mentioned observations of Weigand does the 

 present writer agree. This paper is offered as a preliminary to 

 further work on the chromosome. 



To Professor Guyer, at whose suggestion the work was under- 

 taken, the writer is much indebted for valuable assistance. 



497 



