Schneider : the phenomena of symbiosis. 939 



each other as well as upon marine animals. Higher plants are 

 often parasitic (Mistletoe, Dodder, Indian Pipe, etc. ) Proto- 

 zoa occur parasitically upon animals. An amoeba like organ- 

 ism is said to cause malaria. Different varieties causing 

 different forms of malaria have been described. Higher ani- 

 mals occur in and upon animals and plants, producing manifold 

 injurious effects. The instances of parasitism are, in fact, too 

 numerous to mention. 



Most interesting is the phenomenon of sex-parasitism in 

 which one sex, usually the male, lives parasitically upon the 

 other. In one of the parasitic crustaceans the male is entirely 

 dependent upon the female for its sustenance. Among the 

 Bouellias the male is represented by a mere fertilizing struct- 

 ure parasitic within the reproductive organs of the female. 



In conclusion, we will mention the parasitic relationship of 

 embryos and the mother-organisms. This has already been 

 referred as a questionable form of symbiosis. Klebs is, how- 

 ever, of the opinion that it is true parasitism. The embryo of 

 a plant derives all its nourishment from its parent, and in addi- 

 tion takes from it certain materials which it stores for future 

 use (cotyledons, endosperm). Even after birth the young of 

 many animals remain in parasitic association with the parent. 

 Of the numerous eggs in the black salamander only one devel- 

 ops a young animal, which eats the remaining eggs. 



3. Saprophytism. — Saprophytism is not symbiosis and will 

 be dismissed with a few words. This is a condition which in 

 many instances was no doubt phylogenetically derived from 

 parasitism as we have all gradations between obligative para- 

 sites and obligative saprophytes. In some instances sapro- 

 phytism no doubt originated as such. Dead organic matter 

 occurs plentifully everywhere and forms a suitable substratum 

 for a number of animal as well as vegetable organisms, having 

 special morpho-physiological adaptations for utilizing such a 

 food supply. This preference was no doubt gradually ac- 

 quired. 



Facultative parasites and saprophytes may of course occur 

 as parasites and in so far belong to antagonistic symbiosis. 



