370 WHITMAN. [Vol. IV. 



enough to allow of taking the ripe eggs from the ovaries in a 

 few cases. The demonstration of the male pronucleus in such 

 eggs would show that the leech is able to fertilize itself inter- 

 nally. If the male pronucleus were not found before oviposi- 

 tion, and should be found some time after it, one could infer 

 external self-fecundation. If the male pronucleus proved to be 

 wanting in both cases, we should have conclusive evidence of 

 parthenogenesis, provided a considerable number of tests all 

 gave like results, and provided, further, that the rest of the eggs 

 developed embryos. 



The importance of the experiment will be readily seen ; for 

 should self-fertilization be clearly proved under the conditions 

 named, I think that fact, in the light of what we know about 

 the breeding habits, would be sufficient to make it extremely 

 probable that self-fertilization is a normal affair. That view 

 would compel us to look upon the spermatophores attached to 

 the surface as having nothing to do with fertilization. While 

 self-fertilization certainly seems very improbable, we are not to 

 forget that it is a possibility. It is believed to take place in 

 Cestodes, and perhaps also in some Trematodes and Turbellaria, 

 V Baer {Miil. Arch., 1835, P- 224) long ago reported a case in 

 Limncsus auriadaris, and Oken {Isis, 18 17, p. 320) obtained 

 fertile eggs from an individual of the same species reared in 

 isolation. 



5. NepJielis. 



ISAO IIJIMA. Origin and Growth of the Eggs and Egg-strings in Nephelis. 

 Quart. Jour. Micr. Sci. N. S. LXXXVI. April, 1882. pp. 196-197. 



" The anterior portions of two individuals, attached by their suckers 

 to the glass vessel near each other, are spirally entwined in such a 

 manner that the ventral surfaces of their genital bands are always 

 brought into apposition. They maintain this position for a considerable 

 time, now and then changing the direction of their winding, and relax- 

 ing or tightening their hold. Sometimes the act is of short duration, 

 and two or three times renewed at short intervals. At other times, and 

 when disturbed, the act ceases altogether, or else they combine with 

 other individuals. It is evident that there can be no reciprocal fecunda- 

 tion while the leeches are coupling in the position above described. 



'■^ As there is no introinittent orga7i, it is probable that the male orifice 

 with its projriinent muscular lips clasps the female orifice, while the sper- 

 matozoa are forced onward by the action of the efaculatory organ. 



