30 
Messrs Purvis and Warwick, The Influence of 
The influence of spectral colours on the sporulation of 
Saccharomyces. By J. E. Purvis, M.A., St John’s College, and 
G. R Warwick, B.A., Pembroke College, Cambridge. 
[Read 29 October, 1906.] 
The classical researches of Hansen on the sporulation of 
various species of Saccharomyces were confined to the time limits 
at various temperatures, and so far as we know no researches have 
been published on the influence of the spectral colours upon 
the sporulation, although Marshall Ward has noted the destructive 
effect of light on the spores of 8. pyriformis. The aim of 
this preliminary paper is to describe experiments we have 
conducted in the University Chemical Laboratory, showing that 
rays of light of varying degrees of refrangibility influence the 
appearance and production of spores in various species of 
Saccharomyces, and particularly as to the time when the 
appearance of the spores was first visible. The spectral colours 
were obtained by passing the light of a powerful oil lamp 
through various coloured screens, and the Saccharomyces were 
incubated at a temperature of 24 — 25°C. the temperature never 
varying more than half a degree. Pure cultures of various 
species of Saccharomyces were used, and in every experiment 
fresh healthy cultures were developed in sterilised wort before 
seeding them on moist gypsum blocks. Each growth was micro- 
scopically examined, and if the slightest indications of granulations 
were seen, fresh cultures were developed in wort until the cells 
were plump and filled with clear ungranulated protoplasm. They 
were then ready for seeding on the gypsum blocks and the latter 
were placed in position in boxes whose front windows carried 
coloured screens. The cultures were microscopically examined 
from time to time, and the dates, times and conditions of the 
cells are described in the following notes. 
Description of the Apparatus. 
The apparatus consisted of several japanned tin boxes one side 
of each being occupied by a coloured screen. Gypsum blocks 
were placed on the floors of the boxes and they were kept moist 
by a little water carried on the floors. The upper surface of each 
block was seeded with a very thin layer of the Saccharomyces. 
The boxes with their contents were placed in an incubator kept 
at a temperature of 24° — 25°C., and an oil lamp was placed 
opposite the glass door of the incubator so that its light issued 
