784 REPRODUCTIVE ORGANS AND GENITAL ARTERIES. 



11. Reproductive Organs and Genital Arteries. 



The constitution and topography of the generative apparatus of Nautilus are well 

 known but I will consider them here briefly for the sake of topographical completeness, 

 and to point out the relations in the young, and also because I have formerly 1 described 

 the arteries which are distributed to the glands and ducts direct from the heart. 



Owen (1832) stated that the ovary was supplied from the systemic aorta, while 

 Haller (1895) says that it receives branches from what I have called the posterior pallial 

 artery. It is interesting to recall these antagonistic statements concerning the vascu- 

 larisation of the gonad, since they were both made without apparent misgiving, and 

 are both incorrect. Of course the true facts appear more clearly after injection of fresh 

 material, and it would be quite impossible, I think, to discover the true genital arteries 

 by the most careful dissection of ordinary spirit-specimens. 



In young individuals it is evident that the genito-intestinal ligament constitutes 

 the matrix of the gonad, which at its earliest appearance, in my material, is fully formed 

 but of small size, and lies upon and in the right face of the ligament behind the 

 pericardium. This region no doubt corresponds with its seat of origin in still earlier 

 stages, and serves to indicate the primary importance of the genito-intestinal ligament 

 which from an anatomical standpoint represents the true mesentery of the coelom 

 (PL LXXX. fig. 20). 



In later life, when the gonad has greatly increased in bulk, the anterior portion 

 of the genito-intestinal ligament which is inserted into the pallio-visceral ligament (i.e. the 

 perforated septum which separates the pericardium from the perivisceral coelom) appears 

 to be distinct from the rest, and has been named by Haller the genital ligament, but 

 it is not distinct in origin 2 . 



A narrow offshoot from the genito-intestinal ligament is inserted into the distal wall 

 of the stomach and is the gastral ligament (PL LXXX. figg. 20 and 23). The proximal 

 end of the stomach, where the oesophagus enters it and the intestine leaves it, is closely 

 adherent to the wall of the peri-hepatic haemocoel (cf. PL LXXX. fig. 22). 



Anatomical appearances in the young and adult are in favour of the gonad (ovary 

 and testis) of Nautilus having arisen as a simple pouch-like invagination of the germinal 

 epithelium into the substance of the primitive mesentery. There is no evidence of 

 secondary formation of a pouch in actual development, and I do not think that the 

 question of the primitive or secondary character of the gonadic pouch from a phyletic 

 standpoint is of great importance. What is of importance is the fact that the gonad 

 lies in the perivisceral coelom, and the sexual products virtually fall into the latter on 



1 Willey, A., "Letters from New Guinea, etc." Quart. J. Micr. Sc. Vol. 39, 1896, p. 172. 



2 Haller (o^. cit. 1895, p. 202) says : — " ZuvSrderst mochte ich rmttheilen, dass ich das Genitalligament 



und zum Theil audi das Genitointestinalligament fur zwei solche Doppellamellen halte, die die 



doppelte Anlage des Coloms beweisen, da sie meines Erachtens nach die medianerj Beriihrungswande der 

 beiderseitigen Colomsacke darstellen. Hier sind somit diesbeziiglich noch sebr ursprunglicbe Verhaltnisse, 

 ahnlich wie bei den Placophoren, erhalten." This is an interesting conclusion, which my observations support 

 except that I find no necessity for qualifying or subdividing the genito-intestinal ligament. It is the one 

 mesentery, and in this capacity it is a morphological unit. 



