PREFACE 



Small beings may present large problems. Thus far 

 the micro-organisms exhibit attributes more worthy of 

 note than do the scientists who are and should be study- 

 ing them. The recognition and description of the prob- 

 lems constitute, however, the first step in their analysis 

 and solution. 



The problem of body size dates from the days when 

 giants were thought to walk the earth. There are two 

 main reasons for beginning the study of size regulation 

 upon unicellular organisms. First, their patterns and 

 functions are most readily modified by changes of en- 

 vironment, so that influential factors may be quantita- 

 tively identified in isolation. Second, uniparental inheri- 

 tance is the rule, with the result that, in any species, 

 genetically uniform individuals may be obtained for 

 study. This is an advantage which has received too little 

 attention from physiologists. 



To measure and control the environments of organisms 

 the biologist has had to place his pets under laboratory 

 conditions which are often stigmatised as highly arti- 

 ficial. But who can elucidate cause and effect, factor and 

 regulation, among Bacilli coli while living in their usual 

 environments ? On the other hand, it is a common failure 

 not to remember that the environments determine what 

 properties organisms shall exhibit. In many biological 

 studies, just as much natural history is manifested in one 

 set of conditions as in another. 



It is hoped that the data which are analysed and syn- 

 thesized in the following pages have been arranged and 

 weighed as objectively as a live science will permit. 



E. F. Adolph 

 Rochester, New York, 

 March 24, 1930. 



