The Spermatogenesis of Domestic Mammals. 
I. The Spermatogenesis of the Horse (Hquus caballus). 
By 
Kiyoshi Masui. 
(From the Laboratory for Agricultural Zoology. 
Director: Prof. C. Isurxawa.) 
With Plates XI-XIII and two Text-Figures. 
In the present paper I intend to describe the entire spermatogenesis of 
the horse only, but I hope to continue my studies on the germ cells of other 
domestic mammals. The points of special interest in the spermatogenesis of 
the horse are:—the presence of the accessory chromosome, the mode of 
formation of the synapsis, the reduction of the chromosomes, the development 
of the spermatozoa, the fate of the mitochondria and the behavior of the 
chromatoid corpuscles. 
The work was done under the direction of Professor CHIYOMATSU 
IsuikAwA, to whom I here desire to express my sincere gratitude. Thanks 
are also due to Mr. Suzuki, who kindly supplied me with materials. 
I. Materials and Methods. 
The testes of horses at different ages were used. The material was 
chiefly obtained from the Shirakawa Branch of the Remount Depot and from 
the Veterinary College of the Department of War. 
For preservation, it is necessary, as is already known, that the testes 
should be cut into small pieces and then put into the fixing reagents. Four 
fixatives were used; FLEmMMING’s strong fluid, CHampy’s fluid, Boum’s fluid 
[Jour. Coll Agric, Vol. II. No 6, 1919.] 
