Schneider: the phenomena of symbiosis. 933 



I. Incipient Symbiosis (Indifferent Symbiosis). 



Under incipient symbiosis are included the multitudinous 

 phenomena of symbiotic relationships, which have not yet 

 acquired evident antagonistic or mutualistic characters. In 

 many instances there are marked morphological adaptations, 

 but without any apparent corresponding functional activity. 

 In far the greater number of cases there is simple contact re- 

 sulting from over production. In view of this fact one may be 

 criticised for recognizing such relationships as symbioses. 

 From a priori reasoning one is, however, forced to conclude 

 that the first symbiotic activities began with the first contact 

 of organisms. Incipient symbiosis, therefore, forms the basis 

 or common source of all symbiotic phenomena. From it grad- 

 ually emerged highly complicated morphological and physi- 

 logical adaptations of originally distinct organisms. There is 

 also little doubt as our methods of investigation become more 

 highly perfected many of the symbiotic phenomena now con- 

 sidered as indifferent will be relegated to the realms of antag- 

 onistic or mutualistic symbiosis. 



1. Accidental Symbiosis. — This represents the least special- 

 ized form of symbiosis, but is of wider occurrence than all the 

 others combined Accidental symbiosis is represented by the 

 mere coming in contact of two or more morphologically dis- 

 tinct organisms; such contact being, however, sufficiently pro- 

 longed to give it the semblance of a symbiosis. Mere 

 momentary contact is not symbiosis as here understood. 



Accidental symbioses are particularly numerous where there 

 is luxuriant growth, hence where competition is great, as in 

 the tropics and in green-houses. The lower parts of plants in 

 green-houses are covered with bacteria, hyphal fungi, algae 

 and more rarely some of the lower protozoa. The epidermal 

 cells of many plants contain more or less bacteria. Submerged 

 plants are covered with mollusks, hydras, tubullarians, amoe- 

 bas, vorticellas, etc. The larger land and water organisms 

 furnish hiding places and protection for hosts of smaller or • 

 ganisms. In fact, no organism is free from the accidental 

 association with other organisms, omitting of course in all 

 cases the coterie of recognized parasites. 



In all the instances mentioned there is no perceptible evi- 

 dence of either antagonism or mutualism. Injurious results 

 may occur, but they are due to mechanical causes. Slight 

 morphological changes usually result, but such changes seem 



