188 Phvsioloo-je. 



& • 



10. The withering leaves above a portion of the stem killed 

 with steam show all the Symptoms of dying, namely, rapid loss of 

 water after treatment, then a more uniform loss, rounding up and 

 discoloration of the chloroplasts and contraetion of the mesophyll 

 prötoplasts. The leaves are apparently drying, not so mueh from 

 lack of water as on account of the death of the cells from other causes. 



11. Judging from the behavior and disorganization of the leaves 

 on a stem, a section of which has been killed with steam, it is 

 evident that this method of killing the cells is not a satisfactory 

 one in order to settle the question as to the relation of the living 

 cells to sap flow. 



12. Killing a portion of the stem by apptying wax heated to 

 110° C. causes less apparent disorganization of the cells, less injury 

 to the leaves above, and does not cause a marked immediate decrease 

 in the transpiration. 



13. Experiments in which 5—10 cm. of the stem are killed by 

 treatment with picric acid, 95 per cent alcohol, or CuS0 4 , for 36—48 

 hours, show that sufficient quantities of water may ascend through 

 the poisoned portions to suppty the transpiration need for a com- 

 paratively long period (90 days), and to allow the development of 

 new branches. 



14. Certain poisons (picric acid, chromic acid, and HgCl 2 ) may 

 greatly accelerate the amount of water evaporated in poisoned plants. 

 Not all poisons act alike in this respect; HgCl 2 causes the greatest 

 amount of increase in water loss. Moore. 



Palladin, W., Die Bildung des roten Pigmentes an Wund- 

 stellen bei Amaryllis vittata. (Bef. deutsch, bot. Ges. XXIX. 3. 

 1911.) 



Die Zwiebeln, aber auch Stengel und Blätter, bilden bei Ver- 

 wundungen einen lebhaft roten Farbstoff. Dessen Entstehen ist 

 vom Luftzutritt abhängig; doch erhält man nur wenig davon, wenn 

 man die zerschnittenen Zwiebeln an der Luft trocknen lässt. Um 

 den Farbstoff zu gewinnen, muss man die klein zerschnitteten Zwie- 

 beln einige Zeit in Wasser legen, dann mit Glasglocke bedeckt 

 stehen lassen. Mit allerhand Auszügen gelang es nicht oder nur in 

 geringen Maasse, selbst mit künstlicher Oxj^dasewirkung, Farbstoff 

 zu erzeugen; es muss also wohl ein Lebensprozess an der Farb- 

 stoffbildung beteiligt sein. Das Pigment infiltrirL die Zellmembra- 

 nen; es ist in Wasser schwer löslich, leicht löslich in Aethylalko- 

 hol, Methylalkohol. Chloroform u.s.w. Von den bekannten Pigmenten 

 steht es dem Brasilin am nächsten. Hu^o Fischer. 



Pennington, L. H., The effect of long i tud inal compres- 

 sion upon the production of mechanical tissue in 

 stems. (Bot. Gaz. L. p. 257—284. hg. 1—2. Oct. 1910). 



Woody and herbaceous plants were used and the work carried 

 on both in the green house and garden. As the result of a number 

 of experiments it was shown that there was no increase in mecha- 

 nical strength or in the amount or kind of mechanical tissue under 

 the influence of longitudinal compression for the woody stems 

 worked with. In some herbaceous stems the development of mecha- 

 nical strength in the tissues is somewhat retarded by a longitudinal 



