INHERITANCE IN ASEXUAL REPRODUCTION 165 



majority (75 per cent) are positive and the evidence favors the 

 behef in an inheritance of variations within the clone. The 

 great irregularity of the results, however, makes it impossible 

 to draw from them any law of inheritance within the clone or 

 even to be sure that there is any constant tendency toward the 

 inheritance of variations. 



Unsettled questio7is 



Thus the evidence from previous work bearing upon heredity 

 in Hydra must be looked upon as inclusive and the chief problems 

 of heredity and variation as still unsettled. Hanel maintains 

 the existence of diverse races of Hydra which are distinct in their 

 hereditary constitution. This is denied by both Hase and 

 Pearson but upon different grounds. Hanel holds that, within 

 a population, variations are inherited and that selection is 

 effective in isolating the diverse races, within which there is no- 

 inheritance of variations. Hase denies that variations in the 

 character studied are inherited at all and asserts that such 

 variations are purely somatic. Pearson attempts to show that 

 the variations are inherited both within the population and the 

 clone. Analysis of Hanel' s data shows that there is usually a 

 correlation between parent and progeny within the clone; that 

 this may be very high in some cases, and in others, negative, 

 varying around an average of 0.101. Experimental analysis of 

 the cause of this correlation is lacking. 



The chief questions demanding further investigation seem 

 to be the following : Will such a variable character as the number 

 of tentacles of Hydra lend itself to genetic study? Are there 

 other characters of Hydra which vary less within the individual? 

 Given a character which is comparable in different individuals, 

 do races, hereditarily diverse with respect to this character, 

 exist? If there are such races, in what characters do they 

 differ and are they numerous or few? Is there inheritance of 

 individual differences within the population, and if so, what part 

 do diverse races play in this inheritance? Is there actually a 

 correlation between parent and progeny within the clone? 



