1329 
Botany. — “On intravital precipitates”. By Prof. C. vaN WIsSELINGH. 
(Communicated by Prof. Mott). 
(Communicated in the meeting of February 22, 1913). 
The precipitates caused by basic substances in living plant cells 
have long attracted the attention of investigators and the literature 
on this subject is already voluminous. CHARLES DARWIN was the first 
to investigate these precipitates. He *) first mentions the phenomenon 
in his work on insectivorons plants, and calls it aggregation. As 
pe Vries?) has pointed out, Darwin includes two different pheno- 
mena under this name: in the first place, the movements which he 
discovered in the protoplasm of the cells of the glands of Drosera 
rotundifolia and other insectivorous plants, movements which occur 
whenever stimulation causes an increased secretion, and in the 
second place the precipitates which occur in the protoplasm when 
ammonium carbonate is used as a stimulus. 
As Cu. Darwin*) has shown, precipitates with ammonium carbonate 
and with ammonia are also formed in many other cases in living 
plant cells. He stated that the precipitates no longer occur when the 
preparations are heated in water for 2 to 3 minutes to the boiling 
point and on this account he was inclined to consider the reaction 
as a vital one. With regard to the chemical nature and physiological 
significance of the substance of which the precipitates are composed 
Darwin expressed himself very cautiously. He supposed that they 
consist of protein and considered that we have to deal with an 
excretion product. He concluded his last-mentioned paper as follows: 
“But I hope that some one better fitted than I am, from possessing 
much more chemical and histological knowledge, may be induced 
to investigate the whole subject”. From this it follows that Darwin 
may have thought that another explanation of the phenomenon he 
had discovered was also possible. 
Fr. Darwin‘) defends his father’s views, as far as the chemical 
nature of the precipitate is concerned, which ammonium carbonate 
produces in the tentacles of Drosera rotundifolia. De Vrirs®) is 
1) CHARLES DARWIN, Insectivorous plants. 1875, p. 38. Chapter III. 
2) Huao pe Vries, Ueber die Aggregation im Protoplasma von Drosera rotun- 
difolia. Bot. Zeit. 44. Jahrg. 1886, p. 1. 
3) CHARLES DARWIN, The Action of Carbonate of Ammonia on the Roots of 
certain Plants. The Journal of the Linnean Society. Botany. Vol. XIX. 1882, p. 239. 
4) Francis Darwin, The process of aggregation in the tentacles of Drosera 
rotundifolia. Quarterly journal of microsc. science. Vol. XVI. 1876, p. 309. 
) lic. p. 42 ff. and 57 ff. 
