[9] BIOLOGY OF THE RHINE SALMON. 435 
showed ovaria and testicles of at least the same degree of maturity as 
the Basel fish (testicles weighing 7.7 and 6.1 per cent. of the total 
weight of thebody); and the small male fish of the spawning period, 
which had reached us, were fully matured. 
The weights of the respective organs are not the only proofs in favor 
of the further development, in fresh water, of the semen and the oval 
rium. ‘The microscopic examination of these organs shows lively growth 
and transformation, the detailed description of which, however, does not 
belong here. As regards the ovarium: Mr. His has, as early as 1873,* 
described the different stages of development, from the protoplasm-net 
with pale pellets in the meshes of the small eggs of the winter salmon, 
through several stages, to the mature egg, the size of a pea, with its 
skin delicately marked with small vessels, with its germ ready for im- 
pregnation, and the live plasm skin, half-sticky and half fluid, which 
incloses the clear and highly concentrated egg-fluid. I myself have 
watched the transformations of the male organ through all the vary- 
ing seasons. When still resembling an insignificant, shriveled-up little 
strap, the testicles of the winter salmon often weigh only 755 to 335 
of the total weight of the body; with the first warm spring-days, how- 
ever, towards the end of March—sometimes not till May—new life 
seems to be imparted to this organ; more blood is introduced into it; 
the small one-grained cells, in the diminutive shriveled-up canals, sep- 
arate, become larger, form several grains, and finally form large bodies, 
full to repletion with numerous grains. From June to August we find 
dark-red organs, looking as if they were inflamed, and the looks do not 
deceive; for numerous pus-cells—probably originally colorless blood 
particles—are at this period found, between the seminal cells proper, in 
the canals; through their decay they furnish ample food for the further 
growth of the many-grained bodies, and for the further swelling of the 
organ. At the same time the inter-tissue and the walls of the canals 
grow luxuriantly. Rather late, in September, and even in the begin- 
ning of October, after the organ has reached a weight equal to one-half, 
three-fourths, and even more, of the total weight when matured (about 
5 per cent. of the weight of the body), the transformation of the imma- 
ture masses, of the many-grained cells to genuine seminal cells, takes 
place, not merely by bundles or ‘nests”—as occasionally in former 
months—but on a large scale. This is a very interesting process, and 
is accompanied by the most radical chemical changes, new substances 
making their appearance, whilst old ones vanish. In the beginning of 
November the testicles are snow-white, and consist of hardly anything 
but semen, which at every cut oozes out like cream; it is difficult to rec- 
ognize this organ as the same which was observed some months pre- 
vious, say about the beginning of October, when the testicles, though 
of nearly the same size, were a gray jelly-like mass; and still it is the 
same organ, which has only undergone a change. 
*In the work already quoted. 
