830 EXPERIMENT STATION RECORD. 



was essential to that of aerial portions. In these also the young growing leaves 

 could be grafted at their growing points. The first impulse to union was found 

 to proceed from the stalk. Monocotyledons, it was found, could be grafted in 

 regions where cells were still capable of division. 



Heat evolution by wounded plants, H. Tiessen {Beitr. Biol. Pflanz., 11 

 (1912), No. 1, pp. 53-106, pis. 2, figs. 13). — The author studied the thermal 

 effects following the wounding of potatoes, apples, radishes, carrots, and beets. 



The wounding of tissues was followed by a rise of temperature which was 

 greatest immediately at the wounded surface. The duration of this phenomenon 

 Aaried between one-half and 3 days, the elevation of temperature ranging from 

 0.02 to 0.08° C. with an average of about 0.04°. The maximum elevation was 

 reached on an average in 1 hour after wounding (in extreme cases from 15 

 minutes to 3 hours thereafter). The details of the phenomenon were found to 

 vary for different classes of objects studied. Objects of the same kind under 

 conditions exactly alike exhibited individual differences as regards heat response 

 to wounding, while halves of the same object Invariably showed no differences 

 in this respect. 



Arsenic in some parasitic or parasitized plants, F. Jadin and A. Astruc 

 (Compt. Rend. Acad. Sc-i. [Paris], 155 (1912), No. It, pp. 29i-293).— The results 

 of the authors' analyses, carried out with 19 parasitic and 12 host plants, are 

 considered to justify the following conclusions : 



Parasitic plants on hosts growing directly in the soil contain normally a 

 certain quantity of arsenic. Mistletoe, though found growing in unlike regions 

 and on very different kinds of trees, uniformly contains practically the same 

 proportion of arsenic, although the host plants may show an appreciable dif- 

 ference in this respect. It has not been found possible to establish a proportion 

 between the arsenic content of the parasite and that of its host. 



Some quantitative determinations of manganese in plants, F. Jadin and 

 A. Astruc {Compt. Rend. Acad. 8ci. [Paris], 155 {1912), No. 6, pp. 406-J,08).— 

 Continuing the above studies, the authors present their findings as to man- 

 ganese. 



They find this constantly present in plants, thus explaining wholly or in part 

 the origin of this element in the animal organism. The chlorophyll-bearing 

 parts of the plant api^ear to have more manganese than the underground 

 portions. In case of a plant rich in chlorophyll, such as mistletoe, manganese 

 was found to vary greatly from causes not yet ascertained. 



Variations in the proportion of nicotin in different organs of the tobacco 

 plant during its vegetative period, E. Chuard and R. Mellet {Compt. Rend. 

 Acad. Set. [Paris], 155 {1912), No. J,, pp. 293-295 ) .—Analyses were made of 

 leaves, stems, roots, suckers, and buds of tobacco plants taken on July 14, 

 August 9, September 18, and November 4. 



It was found that the nicotin content in the leaves, stems, and roots increased 

 rapidly during the first period ; that in leaves increasetl little during the second 

 and not at all during the third i^eriod ; while in stems and roots it declined 

 steadily after August 9. In the shoots it reached a maximum September 18. 

 In the tips it did not increase after July 14. 



The influence of tobacco smoke on plants, H. Molisch {Sitsher. K. Akad. 

 Wiss. [Vienna], Math. Naturw. Kl., 120 {1911), I, No. 7, pp. 813-838, figs. J,).— 

 Continuing work previously noted (E. S. R., 27, p. 254), the author reports 

 more fully on the effects of tobacco smoke on plants, as follows: 



Micro-organisms were quickly injured or killed by tobacco smoke. Plants 

 showed great differences in their mode of reaction thereto. Tradescantia 

 guianensis, Selaginella martensii, Tolmiea men^iesii, Eupatorium adenophortim, 

 species of Echeveria. etc., suffered little injury or check from tobacco fumes of 



