126 TRANSACTIONS AKD PROCEEDINGS OF TIIK [Sess. Lxvi. 



The Track of Heredity in 1'lants and Animals. 

 By J. Beard, D.Sc. 



(Read 9th Januaiy 1902.) 



Owing mainly to the writings of Brooks, de Vries, 

 Hertwig, Naegeli, H. Spencer, and, above all others, 

 Galton and Weismann, the problems of heredity have 

 occupied a prominent position in the scientific discussions 

 of recent years. 



The progress of research into the life-history of the cell, 

 the structure and functions of the nucleus, the phenomena 

 of cell-division, more especially those of the " ripening " of 

 the " sexual products," have naturally played important 

 parts in these. Indeed, so much has this been the case, 

 that H. r. Osborn might well say " the study of heredity 

 will ultimately centre around the structure and functions of 

 the germ-cells." 



It is not my intention to attempt the task of writing 

 a history of these discussions and theories : what is pro- 

 posed is merely to indicate the broad and obvious bearings 

 of certain of my results, relating to the history of the 

 germ-cells, on the general problem of heredity. 



In order to obtain a clear insight into the process or 

 processes by which, in a wide sense, germinal continuity, 

 resulting in the phenomena of heredity, is brought to pass, 

 it is a requisite postulate, that an uninterrupted and con- 

 tinuous panorama of the whole course of development from 

 one generation to the next should be secured. Heredity 

 must be dependent on some sort of germinal continuity ; 

 whether of a special germ-plasm in Weismann's sense, or 

 a consequence of an uninterrupted sequence of germ-cells, 

 or a result of an intracellular pangenesis, or something 

 else. 



In this way it comes to be a problem of embryology and 

 development, and as such it falls within the province of 

 the embryologist. This being so, is it not remarkable that 

 the chain of germinal continuity should hitherto not have 

 been completely grasped in any single case ? From my 

 researches on the £rerm-cells,^ it is clear that hitherto no 



M. Beard, "The Morphological Continuitv of the Germ-Cells in 

 Raja hatis." Anat. Anz. V. 18, pp. 465-485, 1900. 



