ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 619 



Elasticity of Flexion in Vegetable Organs.*— Dr. E. Detlefsen de- 

 scribes an instrument and experiments by means of which he estimates 

 what he terms the rigidity of the parts of plants, i. e. their power of resist- 

 ance to forces which cause them to bend. 



The apparatus consists of two perpendicular supports with knife-edges, 

 on which rests the object the elasticity of which is to be tested. This is 

 bent by weights suspended to a ring, attached by means of silk threads to 

 a strong wire laid across the middle of the object. The changes of position 

 of the object are observed in a mirror fixed to one end of the apparatus. 



(4) Chemical Changres (including Respiration and Fermentation). 



Intramolecular Respiration.! — Herr N. W. Diakonow has followed 

 up his previous researches on the chemical conditions of cellular life 

 by a series of experiments on cotyledons, seedlings, &c. His general con- 

 clusions are as follows : — (1) The intensity of the liberation of carbonic 

 anhydride by vegetable cells in the absence of the oxygen of the air is 

 determined by the processes of fermentation which take jjlace within these 

 cells ; (2) the chemical action of free oxygen and the process of fermenta- 

 tion represent two chemical conditions which may replace one another in 

 the metabolism of a vegetable cell : (3) without the chemical action of 

 free oxygen, or without the aid of the process of fermentation, which is the 

 only means of satisfying the requirements of a ceil for oxygen in a medium 

 in which this gas is not present, there is no liberation of carbonic anhydride, 

 that is to say, no life. 



Changes in the Proteids in the Seeds which accompany Germinatior.J 

 — Mr. J. E. Green corroborates v. Gorup-Besanez's conclusion that a 

 proteolytic ferment exists in seeds during germination. 



Seeds of Lupinus hirsutus were germinated for a week : they then gave 

 an acid reaction. They were divested of their coats, the cotyledons were 

 ground ; the powder was extracted with glycerin and the extract dialysed 

 till no trace of crystalline bodies formed during germination were to be 

 found in the dialysate. The digestions were made in tubes of dialysing 

 paper, so that the fluid outside enabled the author to see if peptone were 

 formed or not. No trace of peptone passed the dialyser after a week's 

 exposure. 



The extract was acidified with 0*2 per cent. HCl, some boiled fibrin 

 added, and left at a temperature of 40° C. The process of digestion was 

 slow ; but after a time a distinct biuret action was obtained. The course 

 of digestion of the seed proteids was confirmed by examination of the seeds 

 at different stages in natural germination. In addition to the biuret test 

 the following test was also used : — The solution is freed from all other 

 proteids by boiling with freshly prepared ferric acetate, and then treated 

 with acetic acid and phosphotungstate of soda : peptone is thus precipitated. 



The author summarizes his results thus : — 



1. There exists in the seed of the lupin when germinating a proteo- 

 lytic ferment which will convert fibrin into peptone, and then into leucin 

 and tyrosin (thus extending v. Gorup-Besanez's result). 



2. This exists in the resting seed in the form of a zymogen, which is 

 easily converted into the ferment. 



3. The ferment acts best in a slightly acid medium ; its activity is 



* Arbeit. Bot. Inst. Wiiizburo;, iii. (1887) pp. 408-25 (4 figs.). 



t Arch. Slav. Biol., iii. (1887) pp. 6-25. 



X Proc. Roy. Soc. Lpnd., xli. (1886) pp. 466-9. 



2 s 2 



