9 6 



Scientific Proceedings (hi). 



jornicum parasitic on the leguminous trees Acacia greggii and 

 Olneya tesota and of the leaves of the leafy P. cocker ellii parasitic 

 on Popidus wislizeni, Salix wrightii and Fraxinus attenuata. 



Sap was extracted after antecedent freezing of the tissues in 

 an ice and salt mixture 1 to facilitate extraction 2 and the constants 

 determined on the centrifuged sap. 



Table I shows the average values of A and of P as determined 

 from a published table. 3 



TABLE I. 



Freezing Point Lowering A, and Osmotic Concentration, P. 



Parasite and Host. 



A 



P 



Para- 

 site. 



Host. 



Differ- 

 ence. 



Para- 

 site. 



Host. 



Differ- 

 ence. 



P. Californicum 















on Acacia greggii 



2.8l 



2.21 



+0.60 



33-66 



26.57 



+ 7.09 





2.25 



2.10 



+ 0.15 



26.98 



25.24 



+ 1-74 



P. Cockerellii 

















I.92 



I.84 



+ 0.08 



23 05 



22.04 



+ 1.01 



on Salix wrightii 



2.08 



1.74 



+ 0-34 



24.98 



20.88 



+4.10 



on Fraxinus attenuata 



2.20 



I.96 



+ O.24 



26.47 



23-47 



+3.00 



For each comparison the osmotic concentration of the tissue 

 fluids of the parasite is higher than that of the host. Thus the 

 results of earlier investigations in Jamaica and Arizona are 

 confirmed. 



TABLE II. 



Specific Electrical Conductivity, K X io 5 , and the Ratio of K to A, K/A X io 5 . 



Parasite and Host. 



K 



K/A 



Para- 

 site. 



Host. 



Differ- 

 ence. 



Para- 

 site. 



Host. 



Differ- 

 ence. 



P. Californicum 















on Acacia greggii 



2242 



1509 



+ 733 



831 



682 



+ 149 





2471 



2192 



+ 279 



1103 



IO52 



+ 51 



P. Cockerellii 















on Populus wislizeni 



306l 



1990 



+ IO71 



1598 



IO94 



+ 504 





3101 



1582 



+ 1519 



1488 



908 



+ 580 





2399 



1461 



+ 938 



IO91 



749 



+342 



The constants for specific electrical conductivity and for the 

 ratio of electrical conductivity to freezing point lowering appear 



1 Gortncr and Harris, PL World, 1914, xvii, 49-53. 



2 Dixon and Atkins, Sci. Proc. Roy. Dublin Soc, 1913, N. S., xiii, 422-423; 

 Gortncr, Lawrence and Harris, Biochem. Bull., 1916, v, 139-142. 



3 Harris and Gortner, Amer. Jour. Bot., 1914, i, 75-78. 



