On intravital precipitates, 
by 
C. VAN WISSELINGH. 
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 preci- 
pitates. He 1) first mentions the phenomenon in his work 
on insectivorous plants, and calls it aggregation. As de 
Vries”) has pointed out, Darwin includes two different 
phenomena under this name: in the first place, the move- 
ments which he discovered in the protoplasm of the cells 
of the glands of Drosera rotundifolia and other insectivo- 
rous plants, movements which occur whenever stimulation 
causes an increased secretion, and in the second place the 
precipitates which occur in the protopiasm when ammonium 
carbonate is used as a stimulus. 
As Ch. Darwin *) has shown, precipitates with ammo- 
nium 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 
1) Charles Darwin, Insectivorous plants. 1875, p. 38. Chapter III. 
? Hugo de Vries, Ueber die Aggregation im Protoplasma von 
Drosera rotundifolia. Bot. Zeit. 44. Jahrg. 1886, p. 1. 
5) 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. 
