36 West & West,— Observations on the Conjugatae. 
days are not unfrequently exposed to direct sunlight from 
almost the rising to the setting of the sun. We have noticed 
this shallow water become quite warm. What is the effect 
of this prolonged exposure to sunlight and the increase in the 
temperature of the water ? It is certainly not a detrimental 
one, because there is an acceleration in the growth of the 
lower green and blue-green Algae 1 , and the Conjugatae form 
zygospores much more abundantly than they otherwise would 
do : we could multiply instances indefinitely, but the following 
one will suffice. 
From Vehar Lake, Parel, Bombay, we have examined the 
finest specimens of Clathrocystis aeruginosa we have yet seen, 
and these are exposed to direct sunlight every day for weeks ; 
moreover the atmospheric (shade) temperature was 96° Fahr., 
and that of the water 87° Fahr. The material was collected 
for us in 1895 by Mr. S. Tomlinson, C.E., the Government 
Engineer to the Waterworks. 
Yet Mr. Ewart would inform us that prolonged exposure 
to direct sunlight is fatal ! It is so (as we well know) in the 
small vessels of the laboratory, but not in nature 2 . 
There are four methods of reproduction in the Conjugatae : 
by fragmentation of the filaments (asexual) ; rarely in some 
genera by resting-cells or cysts (asexual) ; by conjugation 
with formation of zygospores or carpospores ; and by aplano- 
spores (asexual). Temperature and climatic conditions affect 
reproduction only so far as to promote or prevent it ; they 
have little effect on the method, although an increase of 
temperature considerably helps conjugation, and so far as we 
have observed, a higher altitude (which is usually accompanied 
by a lower temperature) favours the formation of £ cysts.’ 
During conjugation the activity of the filament is increased ; 
even those cells which take no part in it show greater vigour. 
1 Specially noticeable were Clathrocystis aeruginosa and Crucigenia rectangu- 
laris , the latter with single families of 1 28 cells, the normal number being 16 or 32. 
2 The reader should consult the excellent work by Klebs entitled ‘ Bedingungen 
der Fortpflanzung bei einigen Algen und Pilzen,’ chapter on Conjugatae, in which 
he shows (among other things) that they bear intense light very well, and that 
bright light is necessary for conjugation. 
