SYMBIOLOGY — THE BIOLOGICAL RELATIONSHIPS OF ORGANISMS 125 



It is generally admitted that gametic or sexual reproduction secures 

 or attains a union or fusion of extreme variations of living cells which 

 resulted from the variations in environmental influence, which union or 

 fusion produced an optimum adaptability to the causative variations in 

 the environment. Let us suppose that two groups (I and II) of unicellular 

 organisms, perhaps of the amebic type, should by chance be placed in 

 different environments, group I in a medium with an ample food supply, 

 and group II in a medium with insufficient food. The individual cells of 

 group I would grow comparatively larger and become more sluggish and 

 inactive. The individuals of group II, because of insufficient food would 

 become smaller and develop increased motility for the purpose of securing 

 more of the scant food. As a result of this environmental difference 

 there would in time result two sets of living cells derived from one and the 

 same species which would differ morphologically and physiologically. 

 Should these two groups be compelled to continue in these environments, 

 death or extinction would probably follow, on the one hand because of 

 hypernutrition and resulting inertia, and on the other hand because of in- 

 sufficient food. We can imagine the condition of one or more of the 

 smaller and starving but more active cells finding one or more of the hyper- 

 nourished and inactive larger cells and seizing upon these primarily for 

 the purpose of securing a food supply. This attack on the part of the 

 smaller cell would probably result in more or less reaction in the larger 

 cell. Perhaps the withdrawal of some of the proteid excess restored or 

 awakened or aroused some of the lost energy. In brief, the biological 

 association of these different cells proved mutually beneficial. It is 

 reasonable to suppose that such primal gametoid association should be 

 temporary, rather than a permanent fusion, as in the gametic cell fusion 

 in higher plants and animals. Such temporary gametoid cell associations 

 occur in the group Paramecium, and represents the lowest or least special- 

 ized form of sexual reproduction. In the illustration cited, the larger 

 cell might be considered the female gamete and the smaller one the male 

 gamete. There are gametes which appear to be identical as to size, form 

 and color, but it is irrational to suppose that such germatic cells are identi- 

 cal physiologically and chemically. We cannot imagine what might be 

 the gain in the gametic union, either temporary or permanent, of two iden- 

 tical cells. In other words it is extremely doubtful if there are' genuinely 

 isogamous plants or animals. 



We can illustrate the advantages resulting from the union of the 

 properties of two gametes by the classical chart by Wilson. We may rep- 

 resent the properties of the originally somatic cells by the first four letters 

 of the alphabet. In one group of cells the properties developed to the 

 maximum (A, B, C, D), in the second group the same properties were 



