259 
Fungi at various Temperatures, &c. 
and Glomerella rufomaciilans , 3 0 ; for Thielaviopsis paradoxa , 4-5 0 ; and for 
Cep halo theciu m roseum , 6-9°. The minimum temperature for fructification 
is in all cases several degrees higher than that for growth. 
Edgerton ( 3 ) determined the relation of growth to temperature of 
thirty strains of Glomerella . This paper is interesting as illustrating the 
amount of variation as regards response to different temperatures shown by 
organisms which are morphologically very similar to each other. 
Brooks and Cooley ( 4 ) examined in detail the temperature relation- 
ships of twelve fungi which produce rot of apple in storage. For tables 
and graphs of the rate of growth of the various fungi on artificial medium 
and on apple, the original paper should be consulted. The following results 
may be quoted here : 
1. Spores of Alternaria sp., Botrytis cinerea , Penicillium expansum y 
and Sclerotinia cinerea germinated slowly at o° on corn-meal agar medium ; 
spores of Cephalothecium roseum , Fusarium radicicola , Glomerella cingtdata y 
and Pestalozzia funerea failed to germinate at o°, but slowly germinated 
at 5 0 ; spores of Aspergillus niger failed to germinate at io°. 
2. The minimum temperature for the growth of some fungi in the 
case of inoculations on fruit is higher than that for growth on artificial 
medium, and in general the inhibitory effect of low temperature on the 
early phases of growth is more pronounced in the case of inoculations on 
fruit than for inoculations on artificial medium. Again, in the case of the 
weaker parasites, the minimum for growth on the fruit is dependent upon 
the state of maturity of the latter, being lower according as the fruit is in 
a more advanced stage of ripeness. 
3. In the case of Penicillium expansum it was noted that the fungus, 
after starting at ordinary temperatures, was able to continue growth at o°, 
whereas it could not initiate attack at the latter temperature. The authors 
therefore point out the advisability of immediate storage. 
In connexion with the last-mentioned point it is interesting to note 
that Kirchner ( 5 ) records a similar phenomenon for the growth of the roots 
of seedlings. 
The effect on growth of atmospheric composition has been studied on 
a large variety of plants and plant parts. The two factors of importance 
in the present connexion are: (1) the influence of varied concentration of 
carbon dioxide, (2) the influence of varied concentration of oxygen. 
Carbon dioxide. That a concentration of carbon dioxide greater than 
that normally present in the atmosphere accelerates the growth of higher 
plants has been claimed by some workers, e. g. by Demoussy (6), Fischer ( 7 ), 
Chapin (8), and Kisselew ( 9 ). Brown and Escombe (10), however, failed to 
observe any appreciable increase of yield brought about by increased 
concentrations of carbon dioxide, but on the other hand recorded con- 
siderable morphological effects produced in this way (see on this point 
