APOGAMY IN NEPHRODIUM 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 



XCVIII 



Shig£o Yamanouchi 



This preliminary note will give a brief account of my cytological 

 studies on apogamy in Nephrodium molle Desv., which were con- 

 ducted at the Hull Botanical Laboratorj^, the University of Chicago, 

 under the direction of Professor John M. Coulter and Dr, Charles 

 J. Chamberlain, to whom I acknowledge my great indebtedness 

 for their suggestion and assistance in this investigation. 



To undertake the solution of such an important problem as apog- 

 amy, it is absolutely necessary for an investigator to have beforehand 

 a thorough knowledge of the nuclear condition in the normal life- 

 history of a selected form. For this reason I have made a complete 

 study of the normal life-history of Nephrodium in order to obtain the 

 knowledge requisite for an investigation of the problem of apogamy- 



The detailed account of this investigation, with plates and a dis- 

 cussion of literature, will be published later in three successive papers, . 

 entitled ''Sporogenesis;" "Spermatogenesis, oogenesis, and fertili- 

 zation;" and ''A study of apogamy/' 



Mitoses in the sporophyte. — It was very easy to get the successive 

 stages of the process of the vegetative mitoses in various parts of the 

 leaf, but the most favorable figures were obtained during the forma- 

 tion of the sporogenous tissue. 



The resting nucleus in the sporogenous tissue contains a delicate 

 network with one or several nucleoli. Approaching the prophase 

 of the mitosis the network passes into the continuous spirem, uniform 

 in thickness and distributed throughout the nuclear cavity. Two 

 kinoplasmic caps with few fibers are formed at the two poles out- 

 side the nucleus- The nuclear membrane becomes elongated a little 

 toward the kinoplasmic caps and begins to break down at that point. 

 Coincident with this the spirem segments into a number of chromo- 

 somes to which intruding spindle fibers become attached and finally 

 establish an equatorial plate that has a characteristic aspect w^hich 

 will be showm in a final paper. 



i 





Botanical Gazette, vol. 44] 



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