AN ANALYSIS OF Sl-MBIONT REACTIONS 101 



bionts are readily cultivated. The physiological attri- 

 butes of the microorganisms also must be taken into ac- 

 count. The microorganisms responsible for a munber of 

 diseases can be demonstrated in the tissues and in the 

 blood, but attempts at artificial cultivation of the as- 

 sumed causative organism have only resulted in failure. 

 Obviously, if the proper ingredients were supplied in the 

 culture medium, and other crucial factors were properly 

 adjusted, the microorganism in question should grow 

 freely in this situation. The Rickettsia bodies of Rocky 

 IVIountain spotted fever have resisted cultivation in arti- 

 ficial culture media in the experiments of Wolbach, Noguchi, 

 and many other investigators. 



Pathogenic microorganisms exhibit properties that throw 

 light on some of the possible responses of microsymbionts. 

 It has been shown by a number of bacteriologists that the 

 "specificity" of certain microorganisms may be altered 

 when grown in certain culture media. It is also a common 

 observation that the viabihty of some bacterial cultures 

 diminishes with the age of the culture. It has further 

 been established that the morphology of a microorganism 

 may be altered, by changing the environmental factors. 

 Above all, it must be emphasized that our knowledge of 

 the behavior of bacteria is decidedly limited. 



Variations in response of microsymbionts is exempUfied 

 in the luminiferous bacterial symbionts. Harvey ('20, '24), 

 who has especially studied the physiology of biolumines- 

 cence, states that Zirpolo ('17, '22) cultivated bacteria 

 from the luminiferous organ of Rondeletia minor (a squid), 

 while Montora ('22) was unable to grow bacteria from a 

 similar organ in another squid, Hetoroteuthis dispar. 

 Attempts to cultivate bacteria from the luminiferous or- 

 gans in a number of other animals have resulted in failure. 

 It is perhaps this circmnstance, in part, that led Harvey 

 to say. "I beUeve the animals in which luminous sym- 

 biotic bacteria can be demonstrated are relatively few." 



