AGRKTI.TTTRAT. BOTANY, 1129 



it is Itelievod will explain sonio of llu> niorpliological cliaiiK»'s that are described 

 as following exposure of the fusing gametes to the rays. 



The toxic action of certain organic plant constituents, O. Sciiueineb and 

 II. S. ItEEi) (/io/. (Idz., .'/J {IHOS), Xo. .i, pp. l.i-U).t, litis. 7).— Tlie result of a 

 study on the toxic action of certain compounds wlilcli, with few exceptions, 

 occur naturally in plant tissues is given. A large number of compounds were 

 employed, the solutions being made up on the basis of a certain number of parts 

 of the comi)ouud per million of physiologically pure water. The experiments 

 were carried on with wheat seedlings, the effect of the compounds on transpira- 

 tion, green weight, and turgidity, as well as upon the condition of the root tips 

 being noted. 



The data i)resented show that a number of the compounds occurring naturally 

 in plants have toxic effects upon wheat seedlings. The amino-acid compounds 

 disi)lay a relatively low toxicity, with the exception of tyrosiu and aspartic 

 acid, which have a relatively high toxicity toward plants. The pliysiological 

 action of ueurin, choliu, and betaiu shows that with an increase in oxygen there 

 is a decrease in their toxicity. The pyridin compounds employed were all toxic, 

 some of them being fatal to wheat plants in relatively small amounts. Pyridin 

 itself appeared to be relatively less toxic than any of its related comjiounds. 

 The phenol compounds studied displayed varying degrees of toxicity, and their 

 poisonous properties did not appear to depend upon the number of hydroxyl 

 groups they contained. 



While the authors do not claim that there is a decrease in toxic action due to 

 the introduction of oxygen into organic compounds, yet in a number of cases the 

 more highly oxygenated compounds were found less toxic than those containing 

 less oxygen. In some instances a stimulating effect was noted where very dilute 

 solutions were used. This is accounted for by the possibility that when toxic 

 agents are present in small amounts they excite the cells to greater activity, as 

 a result of which the cells are able to utilize more fully the materials at their 

 disposal, or to overcome retarding conditions of their environment. The authors 

 have shown that deleterious waste products are excreted from living plants, and 

 if these products be of the nature of proteids, beneficial conditions may arise by 

 the continual precipitation of the harmful excretions. It is further suggested 

 that the stimulation of plant growtli by small quantities of toxic agents may 

 consist in the removal of deleterious waste products and the maintenance of a 

 sanitary environment for the growing plant. 



Among the substances employed some appeared to have a toxic action mainly 

 upon the growth of the tops of the plants, while others were more toxic to the 

 growth of the roots than to the tops. 



A bibliography is included. 



The antitoxic action of magnesium and potassium, W. J. V. Osterhout 

 {Bot. G«.^., .',5 (IdOS), Xo. 2, pp. 117-12',, fi(/s. 3).— The investigations of the 

 author which showed that potassium may inhibit more or less fully the poison- 

 ous effects of magnesium having been criticised (E. S. R., 19, p. 323), the 

 author has repeated his experiments, covering a wide range of plants. These 

 included some marine algie, fresh water algte, wheat seedlings, and cuttings 

 of Tradescantia and beet roots, and in addition to the chlorids used in the 

 previous experiments, the author introduced sulphates and nitrates. 



The results obtained showed that the magnesimn salts and potassium salts 

 used sei)arately were i)oisonous to plants, but when mixed together in suitable 

 proportions the poisonous effects more or less completely disappeaivd. 



The effect of fungicides upon the assimilation of carbon dioxid by green 

 leaves, A. Amos {Jour. Acjr. Sci., 2 {19011), No. S, pp. 2r,7-2Gi;) .—A series of 

 experiments is reported in which Bordeaux mixture was sprayed on liops, 



