450 BIOLOGY AND ITS MAKERS 



stature, the law of ancestral inheritance, the statistical study 

 of variations in spines, markings on shells, etc., etc. (Galton, 

 Pearson, Davenport). 



Other branches of biology that have been greatly devel- 

 oped by the experimental method are those of bacteriology 

 and physiological chemistry. The advances in the latter 

 have greatly widened the horizon of our view regarding the 

 nature of vital activities, and they compose one of the leading 

 features of current biological investigation. 



Some Tendencies in Anatomical Studies. Cell-Lineage. 

 While experimental work occupies the center of the stage, 

 at the same time great improvements in morphological 

 studies are evident. It will be only possible, however, to 

 indicate in a general way the direction in which investigations 

 are moving. We note, first, as in a previous paragraph, that 

 the improvement in morphology is generic as well as specific. 

 Anatomical analysis is being carried to its limits in a number 

 of directions. The investigations that are connected with 

 the study of cells afford a conspicuous illustration of this 

 fact. Studies in cell-lineage have led to an exact determina- 

 tion of cell-succession in the development of certain animals, 

 and such studies are still in progress. Great progress also 

 has been made in the study of physical structure of living 

 matter. The tracing of cell-lineage is a feat of remarkably 

 accurate and patient work. But, however much this may 

 command our admiration, it has been surpassed (as related 

 in Chapter XI) by investigations regarding the organization 

 of the egg and the analysis of chromosomes. Boveri, Conk- 

 lin, Wilson, and others have shown that there are recognizable 

 areas within the protoplasm of the egg that have a definite 

 historical relationship to certain structures in process of 

 development. This is the basis upon which rests the doctrine 

 of pre-localization of tissue- forming substances within the 

 protoplasm of the egg. 



