512 PROTOPLASM 



human urine, a source of many highly important physiological 

 substances. 



The presence of a growth-stimulating hormone may be the 

 explanation of the experiments of Ferguson and Duggar, who 

 found that a high percentage of germination of mushroom spores 

 in culture was always preceded a few days by the germination of 

 one or two isolated spores. As the tube of a single spore, say 

 at the edge of a culture, reaches the central mass of spores, then 

 all begin to germinate. Cultures of spores into which bits of the 

 mycelium (fungus body) are introduced give almost perfect 

 germination in half the usual time. It appears that the ger- 

 minating spore tube or the mycelium produces a substance that 

 stimulates other spores to more rapid growth. 



In General. — If we define a hormone as a substance that 

 coordinates the functions of organs by exciting them to activity, 

 then it is obvious that whether such a substance is a complex 

 glandular secretion about which we know little or a single element 

 such as boron, it is a hormone; and when we learn more about 

 the complex hormone, we may find that its active principle — 

 the catalyst — is a simple group if not a single element. The 

 word "hormone" is a useful one and need not give rise to mis- 

 understanding if we realize that it refers to any catalytic agent 

 in metabolic or other internal reactions. In this sense, it 

 becomes synonymous with enzyme (at least to some of them) 

 and possibly also with vitamin. Opposition to the hormone 

 concept arises particularly in such picturesque instances as 

 the following : The German philosophical biologist Hans Driesch 

 was seated in his garden with a student and observed a hen 

 peck at her chicks which yesterday she had mothered. Driesch 

 turned to his student and remarked, "Sehen Sie, Herr Doktor, 

 die Liebe ist nur ein Hormon." Whatever our reaction to this 

 statement by Driesch may be, it is yet true that no emotion can 

 exist without its corresponding hormone. 



VITAMINS 



British merchant ships were once humorously referred to as 

 "lime tubs," and British sailors are still called "limies" or 

 "lime juicers," all of which dates back to the day when it became 

 a British law that no British ship should leave port without 



