1919] 



INDEX OF SUBJECTS. 



981 



Pl<inti3 — Continued. 



period betwe<^n blooming and ripening, 



510. 

 permeability. (See Permeability.) 

 photo.syn thesis. (See PliotosyntliPsis.) 

 poisonous, U.S.D.A., 565. 



(See also fipeoific plants.) 

 pollination. (Sec Pollination. > 

 potted, auto-irrigation, 631. 

 radium action on as aifeoted by liirht, 



523. 

 reciprocal transplants, 328. 

 respiration. (See Respiration.) 

 response to stimulus, 222, 724, 725, 

 seasonal behavior, relation to tempera- 

 ture, 819. 

 self-sterility, studies, 223, 430. 

 .shoot-bearing tumors, eflfect on gro^ th, 



728. 

 shoot formation as affected by leaves, 



526, 727. 

 shrinkage and elongation in rapid- 

 growing slioots, 429. 

 spinose, origin and action, 25. 

 stomata, studies, 329. 429, 819. 

 succulence and acidity, variations, 29. 

 succulent, gas interchange, 28. 

 succulent, origin and action, 25, 133. 

 symbiomorphoses through grafting, 



" 522. 

 taxonomic criteria, 330. 

 transpiration. (See Tran.spiration.) 

 underground runners, 522. 

 used as insecticides, 56. 

 variation. (See Variation.) 

 water requirement as affected by en- 

 vironment, 631. 

 wild, of Germany, useful, 742, 743. 

 wilting in relation to rapid growth, 



429. 

 wilting, studies, 329. 

 woody. (See Wqody plants.) 

 Plasmopara inticola, notes, 349. 

 Plat experiments — 



elimination of error, 635. 

 technique, 432 ; Minn., 730. 

 Platycorus !i-Httata, notes, Fla., 548. 

 Platyedra and Pectinophora, synonymy, 



258. 

 Platyterma, notes and new species. 847. 

 Pleococcum popuUnum, notes, 55. 

 Pleospora, ascospore discharge, 746. 

 Pleuro-pneumonia, contagious, prophylaxis 

 and treatment, 576. 



(See also Influenza, equine.) 

 Plodia hiterpunefeTla. (See Indian meal 



moth.) 

 Plow for furrow-manuring citrus groves. 



741. 

 Plowing — 



depths, effect on nitrate production, 



Mc, 623. 

 relation to soil moisture content, 129. 

 tractor, 486, 487, 790, 887, 888; Pa., 



486; U.S.D.A., 289, 384. 

 V. disking, Nebr., 434. 



Plows — 



mole, worked by horses, 586. 



riding, for cotton, U.S.D.A., 696. 

 Plum — 



aphis, mealy, studies, U.S.D.A., 168. 



brown rot, control, 348 ; Iowa, 237. 



brown rot, notes, 844. 



curculio in South Dakota, 59. 



curculio, rojnedies. 341. 



gouger in South Dakota. .59. 



lice, mealy and rusty brown, 59. 



l)oclvet, treatment. 844. 



I'ust, notes, 154. 



sawfly, web-spinning, 59. 



silver leaf, notes. 750. 



tree borer in South Dakota, 59. 

 Plumbing pipe, tests, 587. 

 Plums — 



culture in Minnesota, Minn., 387. 



fruitfulness. relation to weather, 445. 



fruit-setting studies in New Zealand, 

 445. 



pruning and girdling experiments, 445. 



varieties for Minnesota, 147. 



varieties, new. S.Dak., 238. 

 Pneumococcus — 



as affected by vitamins in animal 

 tissue, 574. 



culture, 778. 



infection, chemotherapy, 476. 



inoculations, testing effleienc.y, 577. 

 Pna — 



glumaris as hay crop, Alaska, 30. 



prntensw as hay crop, Alaska, 31. 



spp.. analyses, Wyo., 333. 

 Podnsplurra leucntrlcha, notes, 154, 657. 

 Poison ivy, insects affecting, 759. 

 Poisonous plants, H.S.D.A., 565. 



(See also specific plants.) 

 Poisons, economic, use in California, 662. 

 Polioencephalomyelitis, acute, studies. 876. 

 Polistes spp., life histories, 853. 

 Pollen — 



forest-tree, distribution, 46. 



preservation, 343. 



tube growth, studies, 430. 

 Pollination, studies, 330. 

 Polyneuritis — 



notes, 874. 



studies, 265, 765, 766. 

 Poli/porus (Fomes) lucidus, notes, 658. 

 Folysaccum erassipes, notes, 453. 

 Polysulphid ammonium wash, notes, 751. 

 Polysulphids, alkaline, action on Oidium, 



845. 

 Pomace flies as affected by breeding and 



temperature, 868. 

 Pongamia plahra cake, fertilizing value, 



816. 

 I'opiUa japonica in New .lersey, 666. 

 Poplar — 



balsam, root habit, 634. 



canker, European, in Pennsylvania, 

 546. 



Carolina, diseases and pests, 55. 



girdler, notes, Conn. State, 159. 



