INHERITANCE IN ASEXUAL REPRODUCTION 



167 



and begun to produce buds in their turn, growth is much slower, 

 although the polyps continue to increase in size until the fifteenth 

 day or later. For comparisons of parent and offspring, I have 

 used measurements of the size at the age of seven days, or as 

 near this as was practicable. The figures so obtained are greatly 

 subject to chance variation but are problaby as dependable 

 as any which can be obtained for so plastic an organism. 



Variation in the nu7nber of teritacles of Hydra viridis 



The most frequent number of tentacles (the modal number) 

 found in wild populations of H. viridis is usually 6, sometimes 7, 

 and the normal range seems to be from 4 to 9. Table 5 shows, 

 in percentages, the distribution of variations in H. viridis found 

 by previous investigators. Both local and seasonal differences 

 probably play a part in the production of the differences in these 

 populations. The data shown in table 6 have been obtained 



TABLE 5 



Distribution, in percentages, of variations previously recorded for Hydra viridis 



XO. OF TENTACLES. 



Rand ('99) 



Hathaway ('99). 



Parke ('00) I., 



II. 



III. 



Reese ('09) 



Hase ('09) 



13 



0.5 



TABLE 6 



Distribution, in percentages, of variations in a population of Hydra viridis from 



Baltimore 



Oct., 1911. 

 Oct., 1913. 

 Apr., 1914. 



ME.\N NO. OF 

 TENT.\CLES 



6.988=t0.044 

 6.696±0.015 

 7.393±0.050 



0.8404 

 0.7332 



0.8827 



NO. OF 

 POLVPS 



167 



1000 



140 



