116 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
bryozoa,to Dr. C. B. Davenport,of the University of Chicago; cladocera, 
to Prof. E. A. Birge, of the University of Wisconsin, and flat-worms, to 
Mr. Raymond Pearl, of the University of Michigan. 
NATURAL HISTORY OF THE CALIFORNIA SALMON. 
Mr. Cloudsley Rutter, scientific assistant, has continued his studies 
of the salmon of the Sacramento basin. His field observations on the 
migrations, habits, food, diseases, ete., of the adult and young salmon 
have been supplemented by laboratory work addressed to the embry- 
ology, anatomy, and histology of the species. Much new information 
has been acquired, and additional or confirmatory data have been 
obtained on subjects previously considered. 
Among the topics to which special attention was given, conclusive 
evidence has been obtained as to the essentiaLcompleteness of natural 
spawning and of natural fertilization. It has also been shown that 
the death of the female salmon after spawning is not due to exhaus- 
tion incident to the spawning process, and that the fish remain on the 
spawning-grounds even after all the eggs are extruded and continue 
the spawning exertions until death. Some interesting observations 
were made on the diseases to which the spawning fish are subject, 
fungus and gill parasites being very destructive in September, but 
of only slight effeet in November. Some additional facts in regard to 
the migrations of adults and fry were secured; but the rate of migra- 
tion of adults is still an unsettled question and should be further 
investigated. It would be useful for the fish-culturists on the upper 
waters of the Sacramento to know definitely when to expect a run of 
salmon that had passed a given point in the lower river—say, Saera- 
mento—at a certain time. 
It has been appreciated that by tagging or. branding much light 
may be thrown on the growth and movements of salmon that could 
not be obtained in any other way. Accordingly, tests have been made 
of the relative advantages of tagging fish, of marking numbers or 
characters on their cheeks and opercles, and of mutilating non-vital 
parts in various ways. Some 10,000 eggs were set aside with a view 
to holding the resulting fry until the fall of 1901 and liberating them 
after marking. 
A complete study of the circulatory system of the salmon, with 
drawings, has been made; a full set of drawings has been prepared, 
showing the changes in the alimentary tract of the salmon during 
migration, and material has been preserved for histological study of 
the various organs and tissues. Series of specimens for a full embryo- 
logical study have been prepared. 
In the course of the work along the river a new stream was found 
affording special facilities for artificial propagation, especially in dry 
seasons, like 1900, when many of the fish fail to reach the upper 
courses of the river. This stream, Mill Creek, is already provided 
