OTHER FACTORS

Excerpt

Under the title of "Other Factors" one can include only a few of the many essential organic substances that various animal species seem unable to synthesize. The description of these substances is scattered throughout the vast literature of biology. Many more have probably been missed than have been found. Such substances may seem of little importance at this time, but who can say when the needs of some insect with specific requirements may provide the key for studying the vitamin physiology of higher species? These ramifications of nutrition are well illustrated by the discovery of Trager and co-workers that a factor essential for growth of mosquito larvae is present in normal human urine but deficient in that of pernicious anemia patients.

To appreciate the expanse of unexplored fields in the domain of nutrition, one need merely read some modern work such as "Culture Methods for Invertebrate Animals" by Needham.¹