BIOLOGICAL PHILOSOPHY 407 



similarly be changed from asexual (budding) to sexual. In some plants 

 likewise the kind of reproduction can be determined by external factors. 

 The attraction between the sex cells is in some cases, though apparently 

 not in all, a chemical one. If a capillary glass tube containing a weak solu- 

 tion of malic acid be placed in water containing the sperms of ferns and 

 mosses, the latter are attracted by the acid, and will enter the tube in great 

 numbers. It is a well-known fact that it is very difficult to cross different 

 species of animals, this difference indeed being made the basis for a physio- 

 logical definition of species, those animals which breed together and pro- 

 duce fertile offspring being grouped as one species; and those which do 

 not interbreed, or do not at least produce fertile offspring being classed as 

 distinct. In lower animals union of egg and sperm of different species may 

 be prevented by physical differences such as size, or chemical differences 

 may prevent the development of an egg into which by chance a foreign 

 sperm has entered. Occasional instances of crossing and the production 

 of fertile offspring are known, in crosses of hares and rabbits, various 

 species of fish, etc. Loeb has succeeded in cross-fertilizing the sea urchin's 

 egg with the sperm of several species of starfish and one of the brittle stars, 

 by simply adding a little sodium hydroxide or carbonate to the water con- 

 taining the eggs. 



Far distant though we be from a solution of the "riddle of life" our only 

 present hope of ultimate success is to proceed from the known to the un- 

 known, working on the hypothesis that nature is a unity and not a duality, 

 and that the same fundamental laws control organic and inorganic worlds 

 alike. 



TELEOLOGICAL ARGUMENTS * 

 ARCHIE J. BAHM 



Arguments for the view that the world has a purpose are many and 

 devious and based often upon curious and dubious premises. In the fol- 

 lowing, some of the more typical arguments have been selected, stated, 

 and "refuted" — refutations consisting of criticisms typically raised against 

 the arguments. Insofar as the case for the view is refuted, the case against 

 the view is not thereby established. This case must be established on its 

 own account. Arguments for the view that the world has no purpose, and 

 criticisms of these arguments, have not been included here. As to the valid- 

 ity either of the arguments or of the criticisms, the reader will judge for 

 himself. 



Design. Familiar to all is the argument that "the world has a pattern and 



* Reprinted by permission of the Scientific Monthly, American Association for the 

 Advancement of Science. Copyright 1944. 



