44 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
I was led to undertake this study while engaged in the microscopic 
study of the circulation of the blood through the excised heart of 
this butterfly—a study which revealed not only innumerable small 
bodies in the blood resembling corpuscles, but also the fact that the 
periodic contraction of the heart, the heart beat, is not confined to 
the heart, and is not controlled bv the ventral nerve cord. While 
engaged in this study, I pierced the testis, and was impressed with a 
remarkable quivering of its contents, due, as I supposed, to contact 
with the air, but more probably an electrical effect which I have never 
been able to witness since, notwithstanding repeated attempts to study 
it more minutely. 
The following is primarily an account of my observations. I have 
not deemed it neeessarv to review extensivelv published memoirs on 
cytology, because I assume that my own observations will show their 
bearings on work already published by other workers in this field, 
who are, of course, already familiar with what has been done in their 
special subject. The necessity of keeping my paper within pre¬ 
scribed limits for publication, also permits only a brief historical sur¬ 
vey of the literature. 
I wish to express my gratitude to the librarians of the University of 
California, of the Leland Stanford university, and of the California 
academy of sciences for their kindness in facilitating my work by 
allowing me free access to their respective libraries. Professor Ritter 
has also shown me courtesies for which I wish to thank him. 
Methods. 
1. Teasing testis on slide, and studying with hot stage in normal 
fluids of the testis and normal salt solution. (PL 13, figs. 30, 31; pi. 
14, figs. 43, 44; pi. 17, figs. 151, 152.) 
2. Teasing, fixing, and staining on the slide (pi. 12, fig. 9-23), 
picrosulphuric and Delafield’s haematoxylin. 
3. Killing, hardening, imbedding, and sectioning in usual way. 
By applying various killing reagents to teased material on the slide, 
and noting the effect under the microscope while the reagent was 
acting, I very soon discovered that the most perfect fixation was secured 
by a concentrated solution of corrosive sublimate to which is added 
between one and two percent acetic acid. 
YY ithout teasing the testis, it is placed perfectly fresh into this fluid. 
