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ROBERT A. BUDINGTON. 



atrium is considerably obliterated by the position of the penes; 

 but the remaining space is more or less filled with spermatozoa, 

 as is also the neck of the uterus, although this latter is very 

 narrow and in the sectioned material it shows but a thin trail of 

 sperm. As its wall is heavy with circular muscle, it is probable 

 that it forced its contents along into the uterus while the fixation 

 was still superficial. It also seems likely that few, if any, sperm 

 are retained in the atrium after copulation is over; any such 

 would be expelled through the external pore. The result of 

 copulation will therefore be the reception of spermatozoa into the 

 uterus of each copulant. This sperm mass in the uterus is 

 (at least during copulation as here studied) in the form of a 

 coiled cord or skein-like mass surrounded by mucus. 



Gamble states in the section on Turbellaria in the Cambridge 

 Nat. Hist., Vol. II., p. 38, that the copulatory organ when 

 extended is long and narrow enough to reach up into the neck of 

 the uterus; and that the eggs and sperm meet in that cavity. 

 The present observations do not permit a denial of that state- 

 ment; but the size of the organ as against that of the uterus duct 

 as seen in Fig. 5 seems to make such an insertion, in Planaria at 

 least, very improbable. 



FIG. 5. Transverse section of Planaria at level of atrium, during copulation. 

 A.m., Atrial margin; G.p., Gut pouches; N., Nerve; P., Penis; T., Testes; Ud., 

 Uterine duct; V.d., Vas deferens. 



Again, although it is well known that in many forms the eggs 

 are passed up into the uterus and meet the sperm there, in the 

 present instance the uterus, as shown in sections, contains only 

 sperm embedded in a mucus mass. The statement is often made 

 that the sperm cells are aggregated into spermatophores; in a 



