142 CARNEGIE INSTITUTION OF WASHINGTON. 



PHYSIOLOGY OF FECUNDITY IN THE DOMESTIC FOWL. 



Biometric investigations of the physiology of egg production and the 

 inheritance of egg production in the domestic fowl have been continued 

 by Dr. Harris in cooperation with three of the agricultural experiment 

 stations. These studies have to do with the prediction of future egg 

 production from the record of short antecedent periods, with the rela- 

 tionship between first and second years' production, and with the cor- 

 relation between the record of mother and daughter. Manuscripts 

 giving the results of some of this work are in an advanced state and will 

 be ready for publication shortly. 



OTHER INVESTIGATIONS. 

 STUDIES ON THE PHYSICO-CHEMICAL PROPERTIES OF VEGETABLE SAPS. 



These investigations, which have been under way for the past several 

 years in cooperation with the Department of Botanical Research, have 

 been continued and considerably expanded during the year by Dr. 

 Harris and his assistants. He reports progress along the following 



lines : 



"(1) Osmotic concentration and electrical conductivity of sap properties in 

 relation to growth-form. — A first paper on the problem of the electrical con- 

 ductivity of the leaf-tissue fluids of the Cold Spring Harbor region, to be 

 published with Professor R. A. Gortner, of the University of Minnesota, and 

 Mr. John V. Lawrence, of the University of Chicago, is now ready for press. 

 The results of this investigation, in connection with others carried out 

 earlier, are of considerable interest in relation to the much-discussed problem 

 of the evolution of woody and herbaceous growth-forms. Earlier studies in 

 the Jamaican montane rain forest, in the Arizona deserts, and in the meso- 

 phytic habitats of the north shore of Long Island have shown that the 

 osmotic concentration, as measured by the cryoscopic method, is far higher 

 in the leaf-tissue fluids of ligneous than of herbaceous species. As a result of 

 these studies a definite physico-chemical difference in the leaf-tissue fluids was 

 shown to be associated with the differentiation in growth-habit. In the 

 present paper it is shown, on the basis of a large series of determinations in 

 the various non-halophytic habitats of the north shore of Long Island, that 

 the specific electrical conductivity of the expressed leaf-tissue fluids of 

 ligneous species is lower than that of herbaceous species. Thus, while the 

 concentration of total solutes is higher in the tissue fluids of ligneous species, 

 the reverse is true for ionized electrolytes. An investigation of the correlation 

 between freezing-point lowering. A, and specific electrical conductivity, k, 

 shows that in a series of species there is practically no relationship between 

 these two properties of the expressed tissue fluids. 



" (2) The chloride content of the tissue fluids of halophytic plants. — The osmotic 

 concentration of the tissue fluids of halophytic plants is generally higher than 

 that of comparable gi'owth-forms in non-saline habitats. This may bedue 

 either to the direct absorption of salts from the soil or to the synthesis of 

 larger quantities of organic substances. The solution of this problem is of 

 considerable importance in relation to the more general problem of adjustment 

 and adaptation. Considerable attention has, therefore, been given to the 

 determination of the chloride content of plant saps in relation to osmotic 

 concentration. With the cooperation of Mr. John V. Lawrence, of the 

 Department of Physiological Chemistry of the University of Chicago, satis- 



