Contributions from the Biological Laboratory of the U. S. Fish Commission, 
Woods Hole, Massachusetts. 
SOME CHEMICAL CHANGES IN THE DEVELOPING FISH EGG. 
By P. A. LEVENE, 
Of the Pathological Institute of the New York State Hospitals. 
The two chief functions of living matter are growing and dying, but of these only 
the latter has attracted sufficient attention of the biological chemist, and our knowl- 
edge of the process of growth remains very unsatisfactory. Most of what has been 
studied in that direction up to the present time has been done by the plant physiolo- 
gist. The developing egg offers very good material for the study of this subject in 
relation to the animal kingdom, hence this work. 
The substances most peculiar to the living organisms are the different nitrogenous 
compounds that take part in the formation of the proteid compounds and reappear on 
the decomposition of the latter. These compounds may be classified in a general way 
into two groups: First, those consisting of carbon, hydrogen, oxygen, and nitrogen; 
and, second, those in which some other elements, mainly sulphur, phosphorus, and 
fluorin (each of them separately or all together) join the former in the formation of 
their molecule. 
The first group may be again divided into substances with a well-defined acid 
nature, as the monoamido acids, like leucin, and into those of a well defined basic 
nature, which are very numerous and quite different in their composition. 
The second group may be divided into simple proteids, containing only carbon, 
nitrogen, hydrogen, oxygen, and sulphur, and combined proteids as nucleo compounds, 
mucin, etc. It is the molecule of the latter compounds that may contain, besides 
carbon, hydrogen, oxygen, and nitrogen, also phosphorus and fluorin. 
The aim of this work was to study the distribution of nitrogen between the main 
groups just enumerated, in different stages of the development of the egg, or, to be 
more precise, to attempt to estimate the quantity of nitrogen in the form of compounds 
not basic by nature, like amido acid, those in the form of bases, and finally those in 
the form of proteids. Further, an attempt was made to ascertain whether in the course 
of development a new formation of the combined proteids (only the nucleo-compouuds 
were dealt with) was taking place. The amounts of ash and water were also estimated. 
The material used was the egg of the cod. It was examined in the following four 
stages: Unfertilized, 24 hours after fertilization, 11 days after fertilization, and about 
20 days after fertilization. All the material was furnished by the courtesy of the 
United States Fish Commission from its station at Woods Hole, Massachusetts. 
