284 
Platybdella Anarrhichae 
and also the testes, which are unduly large and prominent in proportion 
to the wddth of the abdomen. In the leech mounted in balsam as a 
transparent, unstained, microscopic object five pairs of such, large, 
white, glistening, pear-shaped, obviously-chambered organs can be 
easily seen, though, while being equidistant from each other, there is 
considerable space between the first pair thus seen and the post-clitellar 
cincture. Thinking that van Beneden and Hesse might well have 
overlooked the first pair in their dissection, and that Johansson was 
not likely to be wrong, I. cut transverse and longitudinal sections of 
a good many leeches but failed to discover any trace of a first pair of 
testes; what I did discover, however, is sufficiently interesting, namely, 
that the space that presumably should be occupied by a first pair of 
testes was filled by very extensive dilations of the vasa deferentia 
Fig. 7. Platybdella anarrhichae. High magnification of the genital apertures, m.g. male 
genital aperture; f.g. female genital aperture. 
containing spermatoblasts and spermatozoa in all stages of develop¬ 
ment, thus functioning as vesiculae seminales (Fig. 11) though not 
comparable to the structures so named in Calliobdella lophii. This 
enlargement of the vas deferens may possibly account for the abortion 
of the first pair of testes. 
As to whether any trace of a functionless first pair of testes remains, 
as Johansson suggests it should, I am unable to speak with certainty. 
On the whole I think not. Only in one case did I notice any body that 
might remotely resemble one. The specimens were not sufficiently well 
preserved however to speak positively as to their absence. On the 
other hand it is not certain that Johansson has examined Platybdella 
anarrhichae on this point, and while in this leech it is the first pair of 
testes that is reduced or absent, yet, from the purport of his remarks 
