INHERITANCE IN ASEXUAL REPRODUCTION 



169 



data verify these results for H. viridis. Figure 1 shows the mean 

 number of tentacles of about 30 polyps from two different clones 

 at successive intervals of two days. 



Besides the specific tendency to change the number of ten- 

 tacles with advancing age, there are environmental factors which 

 ma^^ produce variation in the number of tentacles of Hydra. 

 Hanel's data, table 7, show that starvation partially inhibits 



)_ tentacles 



Fig. 1 Increase with advancing age in the average number of tentacles of 

 polyps from two clones, A and D. The averages are based upon about 30 polyps 

 from each clone. Clone A shows an average daily increase of 3.6 per cent; clone 

 D an increase of 2.0 per cent. 



the addition of tentacles and causes some to be absorbed. Parke 

 has shown that other unfavorable conditions, such as stagnant 

 water, have a like effect. Injury and regeneration of the oral 

 end also leads to a reduction in the number of tentacles (Rand '99). 

 These factors produce variation in adult Hydras, but further, 

 as will be shown, they have a like effect upon the buds produced 

 by these adults. 



