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HERBERT H. BROWN. 
hsematoxylin the history of the process and the structure of 
the nuclei can be made out. 
(2) Sections stained with gold. Small pieces of the fresh 
testis were soaked in chloride of gold solution, 1 per cent., for 
one hour, after previous immersion in lemon-juice or dilute 
formic acid, and exposed to the direct sunlight of midsummer 
in distilled water acidulated with acetic acid, until the reduc- 
tion of the gold was complete. Then the pieces of tissue were 
carefully and gradually dehydrated with alcohol, and sections 
prepared by the paraffin-shellac method. These preparations 
show in particular the protoplasmic structures and the outlines 
of the cells, the nuclei being entirely unstained and appearing 
like vacuoles; thus they present a marked contrast to the 
haematoxylin-stained sections. 
(3) Sections stained with osmic acid, prepared by soaking 
small pieces of the fresh testis in osmic acid solution, 1 per 
cent., for two days, washing with water, and dehydrating carefully 
with alcohol. Then the sections were prepared by the paraffin- 
shellac method, and mounted in balsam. 
(4) Teased osmic acid preparations. Small pieces of fresh 
testis were soaked in osmic acid solution 1 per cent, for two 
days, and small pieces of tubules were broken up with needles 
in glycerine and water. 
From these teased preparations the development of the 
spermatozoa themselves can be best studied. 
Nomenclature. 1 — I shall first describe the different cell- 
elements contained in a tubule, and give them the names 
which I propose to adopt in this account, and then trace out 
what I consider to be the history of the development of the 
spermatozoa. 
1 The question of nomenclature presents some difficulty, since so many differ- 
ent names have been given to the same elements by different observers, which 
leads to confusion in the mind of the reader; consequently I have, at the 
suggestion of Professor Lankester, avoided the use of such general terms as 
“ spermatoblast,” “spermatocyte,” &c., and have substituted simple descrip- 
tive expressions, descriptive of the appearance or function of the elements of 
the tubule. I may here mention that 1 am much indebted to Professors Schafer 
and Lankester for their kindness in offering suggestions and advice. 
