Origin of Sexuality 295 



were placed side by side a white ear, a dark slate-colored ear, 

 and a black ear were evident. So the writer would candidly 

 state that he has little faith in much of "Mendelian" litera- 

 ture, though he gladly welcomes and profits by the valuable 

 and suggestive nature of Mendel's experiments, as by those of 

 the older hybridizers of last century, and of the present. 



Fourth: Another and highly intricate question involved 

 in sexuality is as to why and hoAv sex-cells have slowdy evolved 

 from ordinary somatic cells; also why and how they have 

 been able to acquire, to lock up or epitomize in their substance, 

 and to transmit to succeeding progeny all of the characteristic 

 somatic details shown in the individuals from which they are 

 derived. 



In study of this question, and as a result in part of what 

 has gone before in this chapter, we accept it as demonstrated 

 equally for plants and animals : (a) that sex cells are extremely 

 stable units, which hand down hereditary details with mar- 

 velous exactness, and which are only slowly and indirectly 

 modified by action of environal agents; (b) that, from the 

 simplest fungi and algae upward through the scale of plants 

 and animals, the sex cells have been derived evolutionarily 

 from somatic cells, which have gradually undergone cytological 

 changes that make an adjoining cell of a filament, then dis- 

 tinct cells of distinct filaments or individuals equally coni- 

 plemental and attractive to each other; thereafter that increas- 

 ing growth in protoplasm and nucleus in occasional cells of 

 one plant or animal with decreasing growth or division in a 

 complemental cell protoplasm and its nucleus of the same 

 or of another plant or animal originates the unequally sized 

 but com])lemental egg and sperm; (c) that the two gametes 

 thus formed have developed equally or more or less inietiuallj^ 

 balanced states of plus and minus cognitic energy, so that 

 they are ecjually attracted, or one attracts and the other is 

 attracted; (d) that in all the simi)ler i)lants and in groups of 

 simpler animals no indication of segregation into somatoplasm 

 and germoplasm occurs, but in higher plants and animals 

 such is gradually established. 



