Apogamy in Nephrodium

Shigéo Yamanouchi
1907 Botanical Gazette  
This preliminary note will give a brief account of my cytological studies on apogamy in Nephrodium molle Desv., which were conducted at the Hull Botanical Laboratory, 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 apogamy, it is absolutely necessary for an investigator to have
more » ... nvestigator to have beforehand a thorough knowledge of the nuclear condition in the normal lifehistory 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 discussion of literature, will be published later in three successive papers, entitled "Sporogenesis;" "Spermatogenesis, oogenesis, and fertilization;" 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 formation 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 outside 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 chromosomes to which intruding spindle fibers become attached and finally establish an equatorial plate that has a characteristic aspect which will be shown in a final paper. Botanical Gazette, vol. 44] [I42 This content downloaded from 080.082.
doi:10.1086/329296 fatcat:zt4kxzrsknc6lbqp3onnd3bopm