4 
C. A. LUDWIG 
Molisch has shown (ii), as was mentioned above, that the growth of 
Phycomyces nitens is slowed down by smoke; and Thorn (i6) has 
reported that in an atmosphere of carbon dioxide no one of the species 
of PenicilHum with which he worked showed growth within a week 
but that development set in after the tubes were restored to the air. 
Richards and MacDougal (13), working with Nitella, found that 
this plant could live in carbon monoxide of 80 percent concentration 
but it was somewhat paler than the check in air. 
Working with certain other algae, Woycicki (17, 18) has shown 
that illuminating gas will induce certain remarkable alterations both 
in the shape of the cell and in its internal structure. With species of 
Spirogyra, Cladophora and Mougeotia he found that in many cases 
curious outgrowths of the cells were produced which often resembled 
holdfasts, while the contents of the cells became more or less dis- 
organized, according to the strength of the gas. The cells, in fact, 
were often killed; and the filaments usually became broken up into 
small pieces or even into the individual cells. Cladophora fracta var. 
horrida showed a much smaller degree of sensitiveness than Spirogyra. 
It was found also that the laboratory air often contains enough gas 
to induce alterations in the algae and that carbon monoxide and 
acetylene are capable of calling forth the changes. 
Langdon (9, 10) has recently made the somewhat remarkable 
discovery that free carbon monoxide occurs in the floats of a Pacific 
marine alga, Nereocystis luetkeana, sometimes to the extent of 12 
percent of the enclosed gases. The range was found to extend down 
to I percent, while the average was about 4 percent. This is inter- 
esting in view of the generally accepted belief in the poisonous nature 
of carbon monoxide to plants, since it shows that at least some plants 
capable of conducting photosynthesis contain tissues which are tolerant 
of quite large amounts of the gas. 
INVESTIGATION 
Organisms Used and General Methods 
The organisms used in the study here reported consisted of bacteria 
and fungi. Of these, a number, Bacillus stihtilis Cohn, B. Kieliensis 
(Lehm. and Neum.) Mig. ("ruber of Kiel"), B. pyocyaneus Gessard, 
B. rubidus Eisenberg and Sarcina lutea Schroter, were obtained from 
the department of bacteriology of the University of Michigan. A 
