52 SUMMARY OF CURRENT RESEARCHES RELATING TO 



diverging from the nucleus to the crystals. Immediately the crystals 

 are formed both striations* and nucleus disappear. "When raphides are 

 being formed, the wall of an adjacent and more internal cell disappears, 

 while its nucleus and protoplasm fuse into a single mass ; several 

 neighbouring cells behave in a similar way, until a single large cell is 

 formed containing a large central nucleus, from which raphides diverge. 

 As before, completion of the crystals is accompanied by disappearance 

 of the nucleus. The author believes this to be the first instance 

 described of such a fusion, and regards it as having great significance 

 in proving the intimate relation of the nucleus and the physiological 

 processes of the cell. 



Movements of Plasmodia.* — V. Vouk publishes the second part of 

 a paper dealing with the rhythmic movements of Didymium nigripes and 

 Chondrioderma difforme. The chief results are as follows : The stream- 

 ing starts in the plasmodia and is of a slow amoeboid nature. The 

 amplitude of the movement is the course traversed by a particle of the 

 plasma, and it increases with the circumference of the plasmodium. 

 The duration of the movement is proportional to the amplitude. The 

 movement itself is very sensitive to light, the ultra-violet rays being 

 specially harmful ; it is uninfluenced by gravity, and there is no evidence 

 of geotaxis. Poisons cause degeneration of the plasmodia. The in- 

 ternal osmotic pressure of a plasmodium appears to be about ^ of 

 the atmosphere. The author disagrees with Klebsschen, who states that 

 plasmodia never live for more than two or three weeks. 



Structure and Development. 

 Vegetative. 



Cutinization of Roots.f — H. Mager has studied the cutinization of 

 the root of Fmikia Sieboldiana, in order to discover the cause of this 

 general phenomenon. In normal roots examined in July, the epiblem 

 cells were distinctly outlined almost to the growing point and cutinization 

 had already commenced. At a distance of 2 to 3 cm. behind the grow- 

 ing point a single layer of semi-cutinized cells merged into short, usually 

 non-cutinized cells, but whrrever the root had suffered any injury these 

 short cells together with the adjacent parenchyma cells became more or 

 less cutinized. Roots were then cultivated in tap-water and in various 

 culture solutions ; in the former case there was little difference beyond 

 a decrease in the number of root-hairs and later cutinization ; in a 

 complete culture solution there was no important difference at all ; in 

 solutions of higher osmotic pressure cutinization showed a proportional 

 increase. Roots grown in dry earth and in a damp atmosphere in the 

 absence of fluid water also exhibited increased cutinization. At the 

 beginning of November, fresh roots were examined and found to be 

 fully cutinized, but when placed in water or in a culture solution, the 



* Zeitschr. Bot., v. (1913) pp. 405-6. 



+ Flora, n.s. vi. (1913) pp. 42-50 (4 figs.). 



