54 THE UNIVERSITY OF OKLAHOMA 



"crossing-over" which expresses itself in a regrouping of the 

 adult characters in arrangements other than that which the parents 

 displayed. These manifestations of the laws which govern the 

 transmission of characters are examples of the main problem of 

 present day genetics, namely the manner and the mechanism of 

 the distribution of the genes. As information is accumulating upon 

 the manner of distribution, some geneticist are turning their atten- 

 tion to the more fundamental problem of the origin of the genes 

 and the processes by which they may be modified, with the con- 

 sequent production of new races. When this problem shall have 

 been adequately investigated we shall be in a position to affirm 

 the nature of the processes by which evolution has been accom- 

 plished. 



The second of the main trends in zoology is in the study of the 

 cell or cytology. Since the cell is the unit of organization both of 

 animals and plants, its study carries the investigator far into the 

 fundamental problems of life. The great interest in the laws of in- 

 heritance has stimulated much cytological research, for obviously 

 the problems of inheritance are focused in the germ cells. Since 

 the hereditary factors must all be combined in the male and female 

 germ cells it follows that information concerning one field illumi- 

 nates the other. In fact, although cytology has traditionally been 

 the special activity of the microscopist, genetics itself may be 

 looked upon as another means for obtaining knowledge of the 

 cell and in that sense as a branch of cytology. Among the special 

 problems of current cytological investigations, are identification 

 of body character with special chromosomes, the individuality of 

 the chromosomes, the chromosome mechanisrn as involved in the 

 distribution of genes, the cytological basis of Mendelism, the means 

 by which the union of the egg and sperm cell is accomplished in 

 fertilization, structure of protoplasm, especial'-y by micro-dissection 

 studies of the living cell, and the relation of substances of the egg 

 cell to the later developing organs of the embryo. 



Cytology is also closely related to the field of general physiol- 

 ogy as developed in recent years. The ceU is looked upon, from 

 this standpoint, as an object for such experimentation as seeks to 

 apply the laws of physics and chemistry to living protoplasm, and to 

 interpret its functions in terms of those laws. The problems of 

 artificial parthenogenesis (the .development of an egg without the 

 aid of the sperm) of fertilization, of conductivity of stimuli, are 

 now problems of physical chemistry and colloidal chemistry, and 

 the knowledge of the phenomena of osmosis, surface tension, 

 agglutmation, permeability, etc., in their biological applications is 



