THE BIOLOGY OF THE MUD-DAUBING WASPS 55 



All larvae 



All prepupae 



All pupae 



All dead adults 



All emerged adults 



Dead adults + emerged 



Dead adults + pupae 



Larvae + prepupae 



Prepupae + pupae 



One or more of each 



One or more in 4 of the 5 



Of course, by the time we have selected only the nests of 

 five good cells or more, the numbers are so small that the prob- 

 able errors are absurdly high, yet to my mind the evidence 

 gives sufficient and conclusive proof of the point we are seeking, 

 viz., the existence of family tendencies of survivability, entirely 

 apart from environment. In the above we see all or nearly all 

 of the family dying in the same stage or in two consecutive 

 stages at a far higher rate than chance would produce, while 

 in the last two groups of miscellaneous distribution of mortality, 

 where, the chances run vastly higher, the actual occurrence 

 drops proportionately lower. 



So in this heavy elimination which goes on we may justly 

 lay a considerable part of the responsibility upon the parents. 

 In turn they themselves may not have been properly endowed, 

 and we can only regard with the kindliest respect those mothers 

 whose offspring we see surviving in large numbers. There are 

 a few family records which we cannot pass by without mar- 

 velling at their perfection, while at present we can only vaguely 

 say that the best of mothers endowed their offspring with the 

 characteristics that make for survival, and the poor mothers 

 put their young here minus these survivabilities, and they went 

 to the wall in spite of the luxurious ease of their young lives. 



We regret being unable to go further into the details of this 

 fascinating study of inherent tendencies in individual families, 

 but these numbers scarcely warrant further analysis. The 

 problem is pregnant with biological suggestions for anyone who 

 can obtain the material in unlimited quantities, and it lends 

 itself admirably to mathematical analysis for anyone who might 

 care to work it up by such methods. 



