MICHIGAN ACADEMY OF SCIENCE. 
99 
II. MATERIAL AND METHODS. 
Specimen^ of Ceuthophilus latebricola Scudder were collected at 
Woods Hole during the summer of 1909. This species was found living 
under pieces of bark, paper and similar objects in wooded places. Many 
specimens were also found living under and around the decaying curbing 
of an old well. 
The method of preparing the material was as follows: The testes were 
dissected out in salt solution and immediately fixed, some of them in 
Flemming’s strong chromo-aceto-osmic fluid and some in Carnoy’s fluid. 
Flemming’s fluid gave the best results. After fixation the testes were 
hardened for a few days in alcohol and then embedded in paraffin. 
Sections were cut six and nine micra thick. Several staining methods 
were used but Heidenhain’s iron-hemotoxylin, counterstained with 
orange G. eosin or Bordeaux red gave the best results. Flemming’s 
triple stain also proved of value. 
III. OBSERVATIONS. 
STRUCTURE OF THE TESTES. 
The testes of CeuthopMhis latebricola Scudder occur as paired 
organs lying one on either side of the dorsal abdominal wall. They are 
composed of a number of follicles arranged in parallel series along the 
vas deferens. (Fig. 1.) In young individuals the follicles are globular 
in form but in the older insects they become elongate. A short tube con- 
nects each follicle at its proximal end with the vas deferens. 
Longitudinal sections of the follicle show near the distal end a large 
apical cell. This cell can be distinguished from surrounding cells by 
its greater size and different staining reaction. The apical cell is sur- 
rounded by primary spermatogonia, which are arranged in a radiating 
row (Fig. 2). The nuclei of the spermatogonia are eccentrically placed, 
being nearest the side away from the apical cell. The chromatin is 
scattered through the nuclei in the form of fine granules. 
The secondary spermatogonial cells are arranged in cysts or groups 
of cells ; each cyst enclosed in a thin membrane. These cysts persist 
throughout the development of the germ cells, the cells in one cyst be- 
ing all in approximately the same stage of development. An exception 
to this occurs in the case of the primary and secondary spermatocytes. 
Secondary spermatocytes are sometimes found in the same cyst with 
primary spermatocytes. There is a more or less regular succession of 
cysts arranged in the follicle from the distal to the proximal end. The 
older cysts gradually approach the proximal end of the follicle and the 
younger ones develop at the distal end. The cysts at the distal end are 
small, two, three or more occupying the diameter of the follicle, whereas 
in the later stages a cross section often shows one cyst occupying this 
entire space. 
Follicles taken from young individuals in May, 1910, were filled with 
cysts of spermatogonial and spermatocyte stages, whereas material 
taken in late July and August, 1909, had the proximal two-thirds or 
more filled with spermatids and mature sperm. It seems probable from 
