No. 3] SPERM ATOPHORES. 37 1 



" I am unable to say precisely at what time of the year copulation 

 begins ; but I found spermatozoa in the ovaries of one leech on the 

 20th of February, for the first time in this year. The act of coupling, 

 so far as my experience goes, takes place almost always in the morning. 



" Abnormal Copulation. — / have often found individuals with a 

 small, two-horned, whitish body adhering to some portion of the genital 

 band. The position of this cornuous body was always on or near the 

 genital band, sometimes on the dorsal surface, sometimes on the extrejne 

 margin, but more frequently on the ventral suiface than elsewhere. It 

 consisted of two thin-walled bottle-shaped tubes (ca. 5 mm. long), the 

 broader ends of which were inserted, close to each other, into a small 

 disc- like portion. This portion, the margin of which presented a villiform 

 appearance, was partially embedded in the epidermis. Around the disc 

 was a discolored area, which proved to be, on examination of sections, a 

 macerated portion of the epider?nis. The two bottle-shaped tubes were 

 filled with spermatozoa, and opened by meaiis of two distinct holes in the 

 disc. From each of these openijigs a stream of spermatozoa was found, 

 penetrating to a considerable depth into the underlying tissues. In sec- 

 tion the substance of the two-horned body appeared dotted and longi- 

 tudinally striated, but I was unable to recognize any cellular structure. 



" For a long time I was much puzzled as to the meaning of all this, but 

 from further observation was led to regard it as a case of abnormal or 

 unsuccessful copulation. 



" When disturbed during the act of copulation, the two leeches usually 

 separate immediately ; but in one i?istance they did not separate even 

 of ter putting them into chromic acid. On examination I found that the 

 female orifice of each leech was not in contact with the male orifice of the 

 other, but that each individual was attached to the ventral s'urface of 

 the other by its male orifice, the female orifice remaitiing free. On sepa- 

 rating them by force, each male orifice left the two-hor?ied object on the 

 body of the other. 



" In another instance that came under my notice, only one individual 

 had already deposited the two-horned body, while the other had a mass of 

 spermatozoa hanging from its male orifice. The latter was dissected, 

 and the two-horned body found occupying the whole interior of the 

 ejaculatory organ, with the cavity of which it exactly corresponded in 

 shape. It came out without any resistance. It thus became evident 

 that the two-horned body belongs to the interior of the ejaculatory 

 organ. That it forms no permanent part of the male organ seems evi- 

 dent, from the fact that sections made in the winter show no trace of 

 such a body. / have not thus far been able to determine whether this 

 body for7ns in the case of normal copulation also. As to its mode of 



