No. 2, March, 1921] PHYSIOLOGY 193 



WATER RELATIONS 



1297. RivETT, Maud F. The anatomy of Rhododendron ponticum, L., and of Ilex aquifo- 

 lium, L., in reference to specific conductivity. Ann. Bot. 34: 525-550. 1920. — The series of 

 studies on the anatomy of woods in relation to water-conducting eflBciency is here continued 

 in connection with the evergreen holly and Rhododendron. Sections were cut at many places 

 throughout the length of several different shoots and the following points determined: (1) 

 total area of wood, (2) total area of cavities, (3) percentage of wood occupied by cavities, 

 (4) average area of cavities, and (5) number of cavities per sq. mm. Curves are given to 

 show the variation, with respect to each of these points, from base to tip of the shoots. The 

 results obtained for these two species and for the ash and hazel in previous studies are com- 

 pared. And the results in all four cases are correlated with those of experiments on water 

 conductivity. All four agree in showing a general decrease in absolute conductivity from 

 base to tip, and an increase in specific conductivity up to a certain point followed by a de- 

 crease. The difference in specific conductivity between the two evergreens is in agreement 

 with the difference in percentage of wood occupied by cavities. This is also true in the 

 case of the two deciduous forms. But the specific conductivity of the deciduous forms is 

 higher than that of the evergreens, though the percentage of wood occupied by vessels is 

 smaller. This difficulty is explained by reference to the greater length of the vessels in the 

 deciduous species and the difference in the nature of their perforations.— IF. P. Thompson, 



1298. Steel, T. On water from the roots of the red mallee (Eucalyptus oleosa). Proc. 

 Linn. Soc. New South Wales. 44: 348-352. 1919. — Water was obtained from the water-storing 

 roots of E. oleosa by cutting lengths of roots and allowing them to drain. It was colorless, 

 practically tasteless, and darkened with age and exposure to air. It contained 6G.60 parts 

 per 100,000 of total solids, 24.20 of which were salts and 42.40 organic matter, chiefly tannin. 

 Soda (NajO) and chlorine were found to be high in relation to the other ingredients. Some 

 mallee soil analyses also showed considerable concentration of these substances. It is 

 thought that the root water may be a reserve supply held in special vessels and used during 

 drought. — Eloise Gerry. 



MINERAL NUTRIENTS 



1299. MoRiTA, KoiCHi, AND BuRTON E. LIVINGSTON. Some solution cultures of wheat 

 without potassium. Bot. Mag. Tokyo 34: 71-90. 1 fig. 1920. — Nutrient solutions without 

 potassium produced very satisfactory growth of wheat seedlings for three weeks. About 90 

 different three-salt solutions were used in which the total concentration of the salts corre- 

 sponded to about one atmosphere of osmotic pressure. All of these solutions were without 

 potassium, and of these the ones with the lower concentrations of the di-hydrogen phosphate 

 produced the best plants. — 0. L. Sponsler. 



PHOTOSYNTHESIS 



1300. Briggs, G. E. Experimental researches on vegetable assimilation and respiration. 

 XIII. The development of photosynthetic activity during germination. Proc. Roy. Soc. London 

 B, 91 : 249-268. 1920. — Leaves were kept in an atmosphere of hydrogen, supplied with car- 

 bon dixoide, and the oxygen removed as fast as formed^. This permits measurement of photo- 

 synthesis and maintenance of uniform amount of chlorophyll for considerable periods. Pho- 

 tosynthetic activity lags behind formation of chlorophyll, indicating some additional internal 

 factor as the limiting one. This internal factor increases with age, so that with equal green- 

 ness in two leaves, a few days difference in age causes increased activity. Willstatter's 

 failure to confirm the findings of Irving that young, fully green leaves might show no activity 

 is due to the fact that he used leaves considerably older. A provisional conception of pho- 

 tosynthesis as consisting of diffusion, photochemical, and chemical stages is advanced as a 

 means of analyzing limiting factors under various conditions. — Paul B. Sears. 



