319 
It had been found that these spots do not occur on smoked, 
rubber; and, since smoked sheet and crepe commanded a higher 
market price, the spots were regarded as being of little or no 
economic importance. Recently, however, there has been a decreas- 
ing demand for smoked plantation rubber; and this, coupled with the 
increase in the quantity of spotted rubber in this country, renders the 
matter of some economic importance. 
Investigations were, therefore, commenced for the purpose of 
of ascertaining the cause of the spots. It was inconceivable that 
they were due to chemical changes in the substance of the rubber 
and it appeared probable that they might be due directly or indirectly 
to the growth of a micro-orgasm. The fact that a pink spot had 
been attributed to Bacillus prodigiosus , which occurs in tap and pool 
water in this country, rendered it likely by analogy that the blue or 
bluish brown spot was due to another bacillus and, perhaps, Bacillus 
violaceus. 
Attempts were made to isolate chromogenic bacilli by transfer- 
ing sections of the the spots to bouillon and by grinding the spotted 
rubber with sand in a mortar and making “ poured plates ” in bouil- 
lon-agar. All attempts to isolate chromogenic bacilli, however, failed. 
Recently a method of observing directly the organisms present in 
the spots has become available. It consists in cutting thin sections 
of spotted rubber and dissolving the caoutchouc by means of xylol or 
benzene. If the section be placed on a slide the caoutchouc may be 
thus dissolved and the organism may then be mounted in Canada 
balsam and examined under a microscope. By this method the foil 
lowing observations have been made : — 
The pink spot contains the mycelium of a fungus whose cel- 
walls are coloured pink. Thefayphas vary in size from j microns to 5 
microns and their walls possess an irregular outline. They are much 
branched and frequently septate and at the ends of the branches are 
borne singly what appear to be spores. These spores are unicellular 
and contain refractive globular masses which afterwards become 
brown. 
The pink discolourations on rubber may take the form of small 
isolated spots or may attain a size of one inch in diameter. In some 
cases the discolouration is, however, more diffuse. 
The blue spots may be present on the same sheets as the 
pink spots or they may occur on separate sheets. They contain 
a mycelium composed of hyphas of a dark colour which give rise 
to globose structures occurring in a single chain ; these may or may 
not be spores. Attempts’ are being made to isolate this organism 
and to identify it. 
The black spots sometimes exhibit a definite radial growth from 
a central point. They contain a mycelium which is composed of 
dark-brown hyphas; so far no structures have here been observed 
which can be regarded as spores. 
