534 EXPERIMENT STATION RECORD. 



rennet is also present in the green bark. In the case of the paper mulberry, the 

 green parts of which contain pectase, rennet can be better studied in the bast 

 of the stalk than in the leaves. 



The greening of potatoes, G. Massee {.Jour. Bd. Agr. [London^. 16 (1909). 

 No. 3, PI). 177-180, 2^1. 1). — ^An account is given of three experiments conducted 

 at Kew for the purpose of ascertaining in what way greening of potatoes proves 

 beneficial. 



The experiments showed that potatoes greened by exposure to light do not lose 

 as much water as those kept in the. dark, and that the stai'ch is not transformed 

 into sugar as in case of ordinary storage. A potato not greened was found to 

 lose six times as much in weight as a potato of equal weight that had been 

 greened. The act of greening is said to cause the skin of the tuber to become 

 comparatively impervious to water and gases, and hence there is a relative 

 cessation of growth and loss of weight. 



The greatest benefit derived from greening, it is said, will be obtained when it 

 is practiced in the autumn immediately after the potatoes are dug. In addition 

 to the advantages indicated, autumn greening will to a great extent check the 

 ravages of winter rot, and this treatment will result in the production of short, 

 sturdy, firmly-attached sprouts, which do not break off during planting. 



The anatomy and some of the biological aspects of the " American m.istle- 

 toe." IT. II. York (,BuL Univ. Texas, Sci. Ser. Xo. 1.3. pp. ,31. pis. 7.^).— A study 

 is reported on the anatomy and some of the biological phenomena of the Ameri- 

 can mistletoe (Phoradendron flavescens) . 



The method of dissemination, germination, formation of aerial shoots, rate and 

 period of growth, etc., are described, together with notes on the effect mistletoe 

 has upon its host. The author claims that the mistletoe is disseminated almost 

 entirely by birds. It is a slow grower and its maximum period of growth coin- 

 cides with that of its host, growth apparently continuing throughout the entire 

 summer. 



It is not a total parasite, since it is abundantly supiilied both in its aerial 

 shoots and in tlie haustoria with chlorophyll, and is not entirely dependent upon 

 its host for food substances. Its relation to the host is largely that of a water 

 pai'asite. and the carbohydi'ates it takes from tlie host plant are those which 

 have been stored in the wood. 



In the region covered by the study, the mistletoe favors in its attack the hack- 

 berry, elm, mesquite, and osage orange. The immunity of certain trees to 

 mistletoe is largely due to the character of the external surface and the thick- 

 ness of the outer corky layer. 



It is said that mistletoe does not directly kill the trees, but causes them to 

 become dwarfed and the branches greatly distorted. Indirectly parts or whole 

 trees may be killed through the action of wood-boring insects which first attack 

 the mistletoe and through it the host tissues, leaving a way open for fungi, 

 bacteria, and wood-boring insects. 



The author has carried on some experiments for killing mistletoe w^liich have 

 proved quite successful. These consist of cutting out the aerial shoots and 

 shaving the outer layers of infected regions wuth a drawing knife so as to 

 expose the haustoria 1 portions of the plants. These are then thoroughly coated 

 with coal tar to prevent further development of the haustoria and to keep out 

 fungi and insects. 



Present problems in plant ecology (Ainer. Nat., 1/3 (1909), Nos. 510, pp. 

 356-378; 511, pp. 420-^31; 512, pp. J,72-.'f93).—This is a series of papers pre- 

 sented before the Botanical Society of America at the Baltimore meeting in 

 1909, the titles and authors of the different papers being as follows : The 

 Trend of Ecological Philosophy, H. C. Cowles; Present Problems of Physi- 



