740 EXPERIMENT STATION RECORD. 



Influence of irritation on the growth of unicellular plants, J. Trzebinski 

 {Bui. Mernat. Acad. Set. Cracovie, 1902, pp. 112-130; ah^. in Jour. Roy. Mlcro.^. Soc. 

 [ionrfon], 1902, No. 4, p. 471). — A series of observations was made on the growth of 

 Phycomijces nitens under the influence of various irritants. Mechanical injury was 

 found to lower the turgescenee and retard the growth of the hypha?. Even very 

 slight injuries were found to act to the detriment of the plant. The irritation of the 

 sporangium by means of slender glass rods or similar agents caused an increase in the 

 growth of the stalk. The-vapor of ether induced a more rapid growth when present 

 in an open vessel but if too condensed the growth was entirely stopped. The experi- 

 ments are held to show a marked similarity between the higher and lower plants in 

 response to various stininli. 



The permeability of protoplasm, Van Rysselberghe {Rec. 7/).s^ Bot. Univ. 

 Bruxelles, 5 {1902), pp. 209-249, ph. 6; ahs. in Juur. Roy. Micros Soc. \_London'], 1902, 

 No. 4, p. 442). — Observations are reported on the influence of temperature on the per- 

 meability of living protoplasm. The principal observations were on the contraction 

 and expansion of living elder pith and of the epidermal cells of Tradescantia. It 

 was found that the permeability of the protoplasm increased with the rise of tem- 

 perature. At 30° C. the protoplasm was 8 times more permeable than at 0°. The 

 permeability was found to be greatly reduced but not completely checked at 0° C, 

 and this applied not only to the passage of water but also of substances held in 

 solution. The passage of water was found to take place under greatly reduced 

 osmotic pressures, and it is thought probable that there is no minimum force of filtra- 

 tion below which no passage of water takes place. It was further found that when 

 the cell saj) of the cell was isotonic with a certain solution at a given temperature it 

 remained isotonic with the same solution at all temperatures, providing changes in 

 the cell sap had not taken jjlace by adaptation. 



Predisposition and immunity in plants, H. Marshall Ward {Proc. Comb. 

 Phil. Soc, 11 {1902), pp. 307-328; ahs. in Jour. Roy. Micros. Soc. [London], 1902, No. 

 4, p. 473). — A discussion is given of the predisposition and immunity of certain plants 

 to disease, based upon the author's investigations on the culture of rusts on brome 

 grasses. His studies were confined to inoculation experiments with the uredospores 

 of Puccinia dispersa, and the results obtained led to the conclusion that the source 

 from which the spores are taken and the specific characteristics of the grass inocu- 

 lated must l>oth be taken into account if infections were successful. Certain species 

 of grasses were readily infected by spores taken from individuals of the same species, 

 but were immune to those of other brome grasses in an increasing degree as the 

 species was further removed in its systematic relationship. It was found to be very 

 difficult to inoculate plants from one specific group to another, and although the 

 various characters of the plants were studied the conclusion was reached that the 

 capacity for infection is due to some biological distinction and is wholly independent 

 of the anatomical structure. 



The origin of variegated varieties of plants, E. Laurent {Bui. Soc. Roy. Bot. 

 Belg., 39 {1900) , II, pp. 6-9). — According to the author, variegation is of 2 forms — 

 (1) that which is jiroduced from seeds and whicli may be attributed to some of the 

 phenomena of fecundation, and (2) the variegation which appears in buds, generally 

 designated as .sports. An account is given of observations in a nursery in which varie- 

 gated forms appeared of the common plum, quince, Cerasusacida, Ccdalpahignonioides, 

 Ailanthus glandulosa, Populns c<maden.vs, and 2 varieties of elm. The variation noticed 

 in these trees was that presented in the second category, viz, the occurrence of sports, 

 and although the same trees were cultivated in neighboring nurseries and different 

 parts of the same the variegation was nf)ticed in only one particular region. It is 

 believed that there must have been some substance present in the soil wl)ich was 

 taken up by the roots and carried throughout the plants, affecting the distribution of 

 the chlorophyll. This substance is l)elieved to be some form of xymase and by the 



