PROGRESS IN BIOLOGICAL INQUIRIES, 1921. $1 
winter the number fell to 1,500 per ¢c. ec. In the spring and early summer of 
1920 the number rose steadily to a maximum average of about 30,000 per ce. ¢. 
from the latter part of June to the end of August. During the autumn and 
early winter the number gradually declined to an average of 2,000 bacteria per 
ec. ec. of water. 
Many of the bacteria represent chromogenic forms, and various colors are 
found in the plate cultures. There seem to be some denitrifying individuals 
present, but conclusive evidence of the presence of lime-precipitating forms 
has not been obtained yet. The average size of these bacteria has been obtained 
so that it will be possible to estimate their live weight and dry weight as well 
as the organic matter in them. 
38. Several reports are now in press in the Transactions of the Wisconsin 
Academy which deal with investigations in which the Bureau of Fisheries has 
cooperated. The following may be listed here: “A survey of the larger aquatic 
plants of Lake Mendota,” by R. H. Denniston; “ A quantitative study of the 
larger aquatic plants of Lake Mendota,” by H. W. Rickett; “A quantitative 
study of the bottom fauna in the deeper water of Lake Mendota,” by C. Juday. 
Some chemical analyses of the larger aquatic plants from Lake Mendota 
have also been made, but this has been done independently by the Wisconsin 
Survey. 
4. Various analyses have shown that the quantity of organic nitrogen in the 
lake water itself amounts to five or six times as much as that in the total 
plankton, and Dr. Schuette has been trying to work out a method for the 
determination of this dissolved organic nitrogen which will give results that 
are more satisfactory than the present methods of nitrogen determination. 
The quantities are so small that the methods now used by chemists do not 
always give consistent results. So far no other method has been found which 
will give better results than the standard methods. 
AGAR-AGAR AND OTHER GELATINS FROM SEAWEED. 
It is obviously unfortunate that the United States should be de- 
pendent upon other countries for its supply of a vital necessity. 
Agar-agar is the commercial name applied to a gelatinous product 
which has been imported from Japan, China, and other places, the 
importations in 1919 amounting to nearly half a million dollars. 
The importance of the material is not, however, measured by its 
strictly commercial value. While it is used in making food and 
confections, agar-agar is primarily important because it is a necessary 
medium for bacteriological work, and is therefore essential to medi- 
cal laboratories and hospitals. It is a requisite for certain industries, 
for the maintenance of health, and for national security. 
Marine alge or seaweed have long been used in this country for 
the preparation of gelatins for particular purposes, but only the 
recent investigations, conducted for the Bureau by Dr. Irving A. 
Field,® have revealed the fact that we have possible sources of supply 
for the most valuable gelatin of all in certain species of seaweed on 
the west coast. In the report for the preceding year reference was 
made to Dr. Field’s preparation of a gelatin suitable for use in pre- 
serving fish, and to experiments in producing a substitute for agar 
from Atlantic coast geaweed. These experiments were not successful, 
but it was later ascertained that at least one species of the west coast 
yields agar of the best quality. Agar prepared by Dr. Field and 
tested at the Army Medical School in Washington was pronounced 
equal or superior to the imported agar. Another species yielded a 
product apparently of like quality. The investigation should be 
followed by a field survey for the purpose of definitely locating the 
8 Wield, I. A.: Sources, Preparation, and Properties of Some Algal Gelatines. Bureau 
of Fisheries, Eco-tomic Circular No, 51, issued Oct. 10. 1921, 7 p. Washington. 
