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P. C. VAN DER WOLK, 
grains in these lots of heaped-up rice. If the yellow colouring happens 
during the voyage to Europe from the Indies then there is a very good 
chance of the whole of the infected portion being rejected on the market, 
or that in every instance its price would fall very seriously. 
The European market is very markedly displeased at the presence 
of these “yellow grains“. In my laboratory at the time of writing this 
treatise there was a lot of such rice with about 0,3% of yellow grains. This 
lot had been totaly rejected; about 0,3% of yellow grains was indeed 
considered tobe an “amazing proportion“. A very few yellow grains 
only are quite sufficient to depreciate the value of rice. If the yellow 
discoloration appears during storage in the barns in the Indies, where the 
rice must often remain for several months before shipping, then the pro¬ 
ducers must expent much time, money, and pains in sorting out and 
removing the yellow grains. 
In short, these yellow grains are a veritable nightmare to the rice- 
dealer. It speaks for itself that this phenomenon has been for many years 
the subject of research; and yet one has never, up to the present, been 
able to trace out the quintessence of the matter, the actual cause. Formerly 
indeed the view was announced that yellow rice must be caused by the 
brooding of the rice, and it was reported once that one was indeed 
quite able to cause yellow rice to appear through artificial brooding by 
employing an extra high temperature, so that yellow grains were truly 
more regarded as products of some or other true chemical process. This 
opinion has in the course of time been upheld by many persons. It is 
however very remarkable that not one of them really seriously believed 
it to actually be due to brooding only. All of them are convinced that 
there is also still “something else“ which must take part in it. This 
supposition is truly evident. Indeed those yellow grains certainly do 
not appear regularly in broodin grice parcels, and then on the 
other hand one sees them even in rice which one knows for certain has 
never brooded. So some persons begin to feel more conscious that 
the advent of yellow grains is much more to be attributed to dampness 
in particu la re, so that the “brooding theory“ begins to be discarded. 
2 . 
I have been charged to once more make a systematic enquiry 
into the matter. For this I in the first place repeated the experiments 
with artificial brooding but without results; I have never been able to 
obtain yellow grains in this way. Very soon indeed dit I base the method 
of my experiments on the supposition that the yellow grains might origi¬ 
nate by the infection of some or other organism. To a certain extent I 
had established reasons for such a supposition. I had e. g. cultivated 
more fungi in my laboratory for some time, which fungi were capable to 
a greater or lesser extent of colouring rice grains. Thus there are different 
species of Aspergillus which are able to impart a bright lemon-colour 
of the grains of rice. This lemon-colour of the endosperm is caused by 
the diffusion of a yellow pigment from the mycelium that permeates the 
endosperm. Further I have had a variety of Pénicillium under exami¬ 
nation which gives a dull lemon-colour to the rice grains, besides one 
variety of Pénicillium which trows off a red pigment with which the grains 
are coloured. Sometime ago I found a Bacterium of a yellow colour. 
