328 EXPERIMENT STATION RECORD. 



Carbon dioxid assimilation and the nutrition of plants with formalde- 

 hyde. T. BoKOKNY {Anil, rin/si"!. \rflHgcr], 12S {llillli), Xo. 10-12, pi). ,56"J- 

 '>S(;). — Tlie author reporls liaviuK found that alpe could utilize formaldehyde 

 in niakinj; starch, and hv has continued his experiments, growing cress, peas, 

 and seedlings of other flowering plants in cultures under glass jars in the 

 al»sence of (■.•iri)on dioxid with similar results. The hearing of his experiments 

 on the various hypotheses regarding photosynthesis is discussed. 



Direct assimilation of ammonium salts by plants, II. B. Hutchinson and 

 N. II. .1. Mii.i.KR h/our. Ai/r. .s'cf., .i (lilO!)), No. 2, pp. n!)-l<)'i, pi. J, fign. 2).— 

 From water cidture experiments which are reported in detail the authors con- 

 clude that ■• agricultiH'al jdants of \arious iiinds can produce normal growth 

 when supplied with nitrogen in llie form of ammonium salts under conditions 

 whii-h exclude the possiliility of nilrilic-it ion. Some jilants grow equally well 

 with ammonium salts or nitrate as som-ce of nitrogen. Other plants, while 

 assimilating annnoniacal nitrogen in the absence of nitrates, ai)pear to prefer 

 nitrates. It is less certain whether ammoniiun salts can ever i)roduce better 

 final results than nitrates although we have indications that this may be the 

 case. 



•' Lehniann found that whilst buikwheat failed to grow well with ammonium 

 salts, maize did far better with this form of nitrogen than with nitrates during 

 the first period of growth. I^ater on the nitrate plants recovered, and the 

 annnonia i>lants became unhealthy. Kellner showed that i)addy rice also jtre- 

 fers annnoninm salts to nitrates to commence with, and that nitrates are better 

 than annnoninm salts for the later growth. The best results of all were 

 obtained when ))oth forms of nitrogen were employed together. 



" I'lants which take up nitrogen exclusively in the form of ammonium salts 

 generally contain very distinctly higher percentages of niti'ogen than when sup- 

 plied with nitrates. The question arises whether the high percentages of nitro- 

 gen in leguminous plants may be due to the nitrogen — or most of it — being 

 assimilated in a form more suited to the rapid production of proteids than 

 nitrate." 



A bibliography of .'^.0 references to literature of the subject is given. 



The chlorin content of leaves, A. J. J. Vandevelde {Handel. Vlaamach 

 Xdtinir rn (Icnrcsh: Cong., 12 (1H08), Xo. 2, pp. 225-22!!).— A study was made 

 in l!t(»7 and 1008 of the chlorin content of the leaves of a large number of plants, 

 and according to their maximum content the author has grouped them into 6 

 classes as follows: (1) Those in which the chlorin content increases from May 

 to September, attaining a maximum at that time, (2) those having a maximum 

 in September with a minimum in July, (.'}) a maximum in .July with a minimum 

 in May and September, (4) a maximum in May with a minimum in September, 

 (5) a maxinnnn in May with a minimum in July followed by an increa.se in 

 September, and (0) those in which there is no regular i)eriodicity in regard to 

 their chlorin content. 



The acid excretion of roots, J. H. Aberson (Meded. Rijks Hoogere Land, 

 Tuin en Bo.<ic]ibouwsch., 1 (1908), pp. 1-18, pis. 4; Jahrb. Wiss. Bot. [Prings- 

 heim], .//7 (1909), Xo. 1, pp. 1-56). — A study was made of the excretions from 

 the roots of a variety of plants, and the author found that they were not acid 

 in the usual sense of the word. Where an acid reaction to litmus was observed 

 it was found to be due to phosphoric acid. The concentration of hydrogen ions 

 was found too weak to make the excretions of much value as agents for bring- 

 ing other elements into solution. The hydrogen ions in the carbonic acid given 

 off from the root hairs were found sufficient to bring into solution various 

 elements of the soil, particularly the phosphates. The same was found to be 

 the case with humic acid, the concentration of the excretion being suflScient 



