828 EXPERIMENT STATION BECOED. 



examples of the force exerted during the growth of certain plants as reported 

 by various investigators. 



On the germination of the seeds of some dicotyledons, J. Adams (Sci. Proc. 

 Roy. DuNin Soc, n. ser., IS (1913), No. S3, pp. 467-^99, pi. i).— The author 

 states that " one of the objects of the present investigation was to discover how 

 long the seeds of a particular species lie dormant in the ground before germi- 

 nation . . . Another . . . was to obtain specimens of the seedlings . . . Alto- 

 gether observations were made on 278 species belonging to 190 genera and 58 

 families of dicotyledons." Alphabetical lists are given of the families, genera, 

 aud species employed, nearly all of which were natives of the British Isles. 

 Lists are also given of plants the seeds of which germinate the same year they 

 are produced, of those having subterranean cotyledons, and of species showing 

 irregularity in the number of their cotyledons. 



The largest percentage of seeds almost impervious to water, hence refusing 

 to germinate for a long time (without artificial thinning of the seed coat by 

 means of acids, etc.). was obtained from Vicia sepium. It is stated that the 

 seeds of stone fruits do not usually germinate until the hard protective cover- 

 ing has decayed in the soil, by which time the embryo has had time to mature 

 fully. 



Germination of seeds after chemical treatment and exposure to light, F. 

 Simon {Biochem. Ztschr., 48 (1913), No. 5, pp. JflO-417; abs. in Jour. Chcm.. Soc. 

 [London], 104 (1913), No. 606, I, p. 431). — The author gives in tabular form 

 the results obtained by treating seeds of cress, lettuce, oats, and radish with 

 ferrous or ferric sulphate or with urauyl sulphate, the seeds being subsequently 

 kept in light or in darkness for five days. While after treatment differences as 

 regards percentage of germination appear in case of particular species, these 

 were generally either small or contradictory when all the forms examined are 

 considered, so that no statement of general application is made in regard to the 

 hastening or retarding effect of the chemical treatment. 



Some observations concerning the reactions of the leaf hairs of Salvinia 

 natans, F. M. Andrews and M. M. Ellis (Bui. Torrey Bot. Club, 40 (1913), 

 No. 8, pp. 441-445)- — Experiments were carried out to determine whether this 

 plant may be able to absorb food from fresh or decaying animal matter or 

 other nutritive substance placed on the leaves. Tests were made with various 

 animal substances, a nutrient solution, and cinders and iron filings placed in 

 contact with the leaf hairs. 



" One of the most interesting results was the chemotactic reaction of the leaf 

 hairs . . . The experiment proved that the leaf hairs are capable of exerting a 

 distinct solvent action on the organic matter placed on them." 



Osmotic pressure in plants. — I, Methods of extracting sap from plant 

 organs. II, Cryoscopic and conductivity measurements on some vegetable 

 saps, H. H. Dixon and W. R. G. Atkins (Sci. Proc. Roy. Dublin Soc, n. scr., 13 

 (1913), Nos. 28, pp. 422-433; 29, pp. 434-440) .—The authors claim that the sap 

 pressed from living, untreated tissues does not give a true estimate of the con- 

 centration of that in the vacuoles of the cells of the organ before the applica- 

 tion of pressure, and that in order to extract the sap from the cells without 

 altering its concentration, it is necessary to render the protoplasmic membrane 

 permeable. This, it is claimed, may be effected by employment of liquid air. 

 Discovery of this fact is held to require the correction of certain results pre- 

 viously obtained by the authors (E. S. R., 27, p. 631), and some of the corrected 

 data are given in the present papers in tabular form. It is claimed that the 

 figures previously published were really too low, and that the actual osmotic 

 pressures in the cells are much greater than is required by the cohesion theory 

 of sap ascent, as upheld by Dixon (E. S. R., 15, p. 123). 



