414 



SCIENCE 



[N. S. Vol. XXXVI. No. 92& 



the chemical and physical nature of the com- 

 ponent parts.. J. F. McClendon 

 U. S. Bureau op Fisheries, 

 Woods Hole, Mass., 

 July 20, 1912 



ON THE RELATIONSHIP BETWEEN THE BILATERAL 



ASYMMETRY OP THE UNILOCULAR FRUIT 



AND THE WEIGHT OF THE SEED 



WHICH JT PRODUCES 



The problem of symmetry, radial and bilat- 

 eral, is of such great interest that it can not 

 be approached from too many angles. The 

 purpose of the present note is to discuss on 

 the basis of a rather extensive series of quan- 

 titative data the question : " Do bean pods 

 with an ' odd ' number of ovules produce 

 lighter seeds than those with an even (2, 4, 

 6, etc.) number?" Here the "odd" or 

 " even " character of the pod is to some extent 

 an index of bilateral asymmetry. Pods with 

 an odd number of ovules must have them un- 

 equally divided between the two carpellary 

 margins which form the ventral suture, while 

 those with an even number generally have 

 them equally divided. Thus with respect to 

 the distribution of ovules, pods with an odd 

 number must be bilaterally asymmetrical; 

 those with an even number are generally bi- 

 laterally symmetrical. 



The results which led up to the present 

 study were the discovery of an intra-indi- 

 vidual selective elimination of ovaries with a 

 larger number of " odd " locules in Staphylea^ 

 and the demonstration of a usually lower fer- 

 tility and fecundity in " odd " pods of Phase- 

 olus.' 



^For literature, see: "The Selective Elimina- 

 tion of Organs," Science, N. S., XXXII., 519- 

 528, 1910; "On the Selective Elimination occur- 

 ring during the Development of the Fruit of 

 Staphylea," Biometrika, VII., 452-504, 1910; 

 "Further Observations on the Selective Elimina- 

 tion of Organs in Staphylea," Zeitschrift f. Ind. 

 Ahst- u. Vererbungsl, V., 273-288, 1911; "The 

 Measurement of Natural Selection," Pop. Sci. 

 Mo., LXXVIIL, 521-538, 1911. 



^ " On the Eelationship between Bilateral Asym- 

 metry and Fertility and Fecundity." In press in 

 Eoux's Archiv f. Entwickelungsmechanik. 



Among the series of individually weighed 

 bean seeds gathered for a study of the pure 

 line problem are five in which the number of 

 ovules in the pod from which the seed was 

 taken is recorded. These series (designated 

 by key letters) are : 



L. Golden Wax. Grown at Lawrence, Kan- 

 sas, 1906. 2,861 seeds. 



LL. Golden Wax. Plants the offspring of 

 the L series, grown at Lawrence, Kansas, 1907. 

 3,947 seeds. 



GG. Burpee's Stringless. Grown at the 

 Missouri Botanical Garden, 1907. 8,364 seeds. 



H. Navy. Grown near Sharpsburg, Ohio, 

 1907. 5,778 seeds. 



D. Navy. Another series, grown under very 

 different conditions near Sharpsburg, Ohio, 

 1907. 2,362 seeds. 



The material is, therefore, rather extensive 

 and diversified. Two methods of analysis are 

 possible, (a) The pods may be merely classi- 

 fied as " odd " and " even " and the mean 

 weight of the seeds produced by each kind 

 determined. (b) A regression equation can 

 be fitted to the whole data and the weighted 

 mean deviation 'of the empirical means from 

 the theoretical means determined for either 

 " odd " or " even " pods. 



Let = number of ovules per pod, w ==■ 

 weight of seed in units of .025 grams. Then 

 correlations and regression straight line equa- 

 tions are :^ 



Repression Equation 



10 = 16.4645 — .1597 o 



w = 13.0281 -I- .2060 o 



«; = 17.3881 -1-.0354 o 



w = 11.0961 — .2806 o 



w= 8.5554 — .2583 o 



The correlations are in all cases low. Test- 

 ing the influence of the " odd " (asymmet- 

 rical) character of the pod upon the weight of 

 the seed by the weighted mean deviation (re- 

 garding signs) of the average weights of seeds 

 produced by odd pods from the theoretical 

 means calculated from these equations as well 



" Data from which all the constants given here 

 may be checlied will be eventually published for 

 another purpose. 



