The Critical Environment 7 



of pollen that a yellowish dust is often deposited on all surfaces in the 

 vicinity. A tropical American orchid of the genus Maxillaria is re- 

 ported to produce as many as 1,756,000 seeds per capsule. Spores are 

 produced in astronomical numbers by many lower plants. A conserv- 

 ative estimate made for the downy mildew, Sclerospora, which attacks 

 maize in the Philippines, indicates that as many as 6 billion conidia 

 (spores) are liberated from the fungi parasitizing a single maize 

 plant during one night. Since discharge of conidia continues night 

 after night for months, the intensity of the reproductive capacity of 

 these species surpasses the imagination (Weston, 1923). 



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Hubbs and Eschmeyer, 1938 

 Fig. 1.3. Schematic representation of natural mortality in small-mouthed black 

 bass. Only a few fish survive to maturity from hundreds of eggs laid. 



The adaptations of some plants and animals are more specifically per- 

 fected to their environments, and their reproductive rates can con- 

 sc quently be relatively low, but even slow breeders tend to increase, 

 if the elephant produces only six young in its life time, as has been 

 estimated, these creatures would nevertheless eventually increase to 

 such numbers, if all progeny survived, that they would cover the 

 whole surface of Africa. An even slower breeding rate is exhibited 

 by the California "big trees" (Sequoia gigantea) which do not pro- 

 duce their first seeds until they are 175 or 200 years old! And yet 

 even this species has the capacity to enlarge its population. 



Since no species of plant or animal goes on increasing indefinitely, 

 we are forced to the conclusion that, whether reproduction rate is fast 

 or slow, supernumerary individuals are killed off. Usually most of 

 the young produced die at an early age. In the terms of the insurance 



