NOTES ON RECENT RESEARCH. 



707 



Plants and Electricity. 



Plant Juices, Electrical Conductivity of. By h\ D. Heald (Bot, 

 Guz. xxxiv., No. 2, p. 81). — The experiments described and illustrated 

 were made with Beta vulgaris, Solatium tuberosum, Allium Cepa, 

 Baphanus sativus, Nuphar advena, Cucumis nations, Portulaca, and 

 AmarautJim, and led to the following results : — 



1. Plant juices are good conductors, and the conductivity is due in 

 large measure to the dissolved mineral substances, while the organic 

 compounds play a minor part. 



2. The specific conductivity of the juice obtained from the roots of 

 plants is always considerably less than that of the juice obtained from 

 sub-aerial parts. 



3. The specific conductivity generally increases progressively from the 

 root upward, although in some cases the sap from the stem has a higher 

 conductivity than that from the leaves. 



4. In the majority of cases the specific conductivity is a rough measure 

 of the relative amounts of ash present in different parts of the plant. (Bee 

 also " Electrical.") — G. H. 



Anatomy of Podalyki^: and Geniste^e. 



Podalyriae and Genisteae, Leaf-anatomy of (Beih. Bot. Cent. 

 bd. xii. ht. 2, pp. 279 288). — Dr. H. Solereder gives a short account of 

 the anatomy of these two tribes. The Podalyria possess the charac- 

 teristic hairs of Pajrilionaceat ; they have no glands. The epidermis 

 cells do not possess strongly undulated sidewalls. There is no special 

 type of stoma. The intercellular spaces in the leaf are generally reduced. 

 Both centric and bifacial types occur. Generally sclerenchyma accom- 

 panies the bundles. Idioblasts are found frequently and contain tannin. 

 The Genistece possess the usual leguminous hairs. Glandular hairs 

 occur in Melolobium. Tannin-idioblasts and calcium-oxalate crystals are 

 generally absent, but saponin-like substances, sph;erocrystalline masses, 

 indigo, and indican-like bodies are found. 



A key is given to the chief anatomical peculiarities of the genera in 

 both groups. — G. F. S.-E. 



Submerged Foliage. 



Proserpinaca palustris, On the nature of the stimulus causing the 

 change of form and structure in. By W. B. McCallum ((Dot. Gaz. 

 xxxiv. No. 2, p. 93). — The object of this paper is to discover the actual 

 cause which produces the finely-dissected foliage when submerged, the 

 aerial leaves being narrowly lanceolate and serrate. After showing 

 that light, nutrition, temperature, salts, relations to carbon-dioxide 

 and 0 , and contact stimulus must be eliminated as direct influences, 

 experiments proved that it was the excessively hydrated condition of the 

 protoplasm. " The essential feature common to the water and the moist 

 air (in which the submerged type was also produced) is the inhibition 

 of transpiration and the consequent choking of the cells and diluting of 

 the protoplasm with water." By means of hygrometric salts the proto- 

 plasm was restored to its proper state, and the air type of leaf was 

 developed under water. 



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