695 
The flower of Dendrobium thyrsiflorum. Rehb. fil. 
The flower of Dendrobium thyrsiflorum Rehb. fil., is an example 
of an object containing a carotinoid, differing from those so far 
described. After treatment by the potash method, I found in the 
cells orange-yellow (Kircksmck et Vaterre 151) much curved fila- 
mentous crystals, orange-yellow (151) whetstone-shaped plates and 
large and small aggregates of brightly coloured orange (101 though 
inclining towards orange-red 81) thin acicular crystals. The difference 
in colour is very striking. Some cells are more especially filled with 
one shape, others with the other shape. In this case I could observe 
no difference on using sulphuric acid of varying strength, nor with 
bromine water, but on the other hand iodine in potassium iodide 
solution brings it out. With the latter reagent the orange-yellow 
crystals at once become a fine green. The orange-yellow aggregates 
suffer no change of colour whatsoever, not even after 24 hours. 
The contrast in the colour of the erystals is very striking, So far 
as concerns their solubility in a solution of phenol in glycerine (3 
to 1) the crystals also differ much. When the solvent is allowed 
to flow under the cover-slip, the orange-yellow crystals are at once 
seen to deliquesce, and form with the solvent yellow globules which 
dissolve entirely. On the other hand the orange-coloured aggregates 
do not at first show any signs of dissolving. Sometimes they are 
seen in the midst of the globules that are formed. Finally all the 
orange aggregates can be seen in the yellow solution of the orange- 
yellow crystals. Slowly the orange crystals dissolve also. If the 
preparations are placed for one day in the mixture of phenol and 
elycerine, the orange crystals also dissolve. 
Because of the difference in colour, different behaviour towards 
iodine in potassium iodide solution and different solubility in phenol, 
I conclude that two different carotinoids occur in the flower of 
Dendrobium thyrsiflorum. The one of these which is to some extent 
reddish-orange in colour, is a carotinoid that is not common in plants. 
Such a carotinoid I have found only in Dendrobium thyrsitlorum. 
Its colour and other properties makes me inclined to think that it 
belongs to the xanthophylls rather than to the carotins. 
Haematococcus pluviahs Plot. 
The colouring matter of this interesting alga has been investigated by 
Zoer’). The result of his enquiry was that it possesses not one but two 
1) W. Zoer, Conn’s Hämatochrom ein Sammelbegriff, Biologisches Centralblatt, 
XV. Bd. 1895, p. 417. 
