70- SUMMARY OF CURRENT RESEARCHES RELATING TO 



Finally the daughter-nuclei divide, and are kept together only by a 

 narrow bridge ; when the cell-division is complete, these nuclei are 

 found again on the division-walls. The diameter of these minute 

 bodies is only from • 5 to • 6 /x ; their behaviour when dividing and 

 towards colouring reagents is opposed to the view that they are 

 chromatin or microsomes. 



Influence of Warmtli of the Soil on the Cell-formation of Plants-* 

 — E. Prillieux finds that the eifect of warmth in the earth is to cause a 

 hypertrophy of the interior of the stem in a young plant ; when 

 closely examined, this is found to be accompanied by multiplication 

 of the cell-nuclei. In the bean and the pumpkin, when the seeds 

 have germinated in earth of 10° higher temperature than the surround- 

 ing air, cells are often found containing two or three massed or 

 isolated nuclei, which may be either equal or unequal in size, and 

 of various shapes. This multiplication is effected by fission of the 

 nuclei, which generally contain several nucleoli, up to the number of 

 four or five, of very different forms and sizes, and sometimes obviously 

 constricted preparatory to their division. At the time of division, a 

 boundary wall placed either opposite a large nucleus or between two 

 closely apposed small ones, divides the nucleus into two halves ; these 

 two halves swell up, and the whole has usually a kidney-like shape. 

 The process is completed by prolongation of the grooves of the surface 

 through the dividing wall. 



Growth of Starch-grains by Intussusception.f — In replying to 

 the attack by SchimperJ on the theory of the growth of starch- 

 grains by intussusception, C. Naegeli points out that there are three 

 different conditions of the " micellar " constitution of the cell-wall 

 (using the term " micella " to distinguish the physical ultimate 

 elements of a substance from the chemical molecules or atoms) viz. : — 

 (1) The living condition of the cell-wall, when it is in immediate 

 contact with living cell-contents ; in this condition the cell-wall is 

 more or less strongly coloured by aniline pigments, while the contents 

 do not take up any of them. (2) The cell-wall is in a naturally dead 

 state when the living contents separate from it, or when they die 

 while still remaining in contact with it ; in this condition the cell- 

 wall does not take uji any pigment, while the contents become 

 coloured ; and if the cell-wall was coloured when living, it loses its 

 colour on passing into the dead state. (3) The swollen condition is 

 caused by the action of alkalies or acids, by long boiling in water, 

 or by lying for a sufficient time in cold water ; in this state the cell- 

 wall is again capable of being coloured. 



In every stage of its growth the starch-grain is a material system 

 surrounded by a watery fluid, and saturated with water, the tensions 

 of which are in a condition of equilibrium. When the grain becomes 

 dry, crevices are formed, a proof that the equilibrium is by this means 



* Kosmos, viii. (1881) pp. 63-4. 



t Bot. Ztg., xxxix. (1881) pp. 633-51, 657-77; also SB. Akad. Wiss. 

 Munchen, xi. (1881) pp. 391-438. 



X See this Jouroal, i. (1881) p. 909. 



I 



