578 THE PHYSIOLOGY OF REPRODUCTION 



continue tor ;in abnormally long period. Thus, Williams 1 record* 

 a case of a woman with whom pregnancy extended for over eleven 

 lunar months after the cessation of menstruation, instead of the 

 usual ten lunar months (<>. about 280 days). In this case typical 

 labour pains were experienced at the end of the tenth month, but 

 these subsided after a short time, and were not renewed until four 

 weeks later, when they resulted in parturition. The same woman 

 became pregnant a second time, when the period of pregnam-y was 

 again prolonged until the end of the eleventh month after the last 

 menstruation. The children on each occasion were abnormally lai^i- 

 and heavy at birth. Allen 2 has recently recorded a number of 

 further cases of prolonged gestation in women, the longest time 

 chronicled being .'!34 days. % It is stated that inertia of the uterus 

 (due to fatty degeneration) is frequently associated with prolonged 

 gestation; but the occurrence of the latter is no doubt often brought 

 about by other causes which are at present unknown. 



Cases of prolonged gestation have been observed also among 

 animals. Professor Ewart has informed the writer of a mare in his 

 possession in which the period of gestation was extended to twelve 

 months instead of the usual eleven. Other cases of prolonged 

 gestation in mares, and also in cows, have Ijeen recorded by TessiiM ; 

 and Franck-Albrecht-Goring, 4 and appear to l>e not uncommon. 

 No satisfactory reason has been suggested to account for such cast--. 



According to Pinard 5 prolonged gestation may occur in Rodents 

 (Dipodillus siiitoni, Merioiies shawi, M. longifrom, MH* /////.ST/////X, etc.), 

 as a result of suckling a large litter produced just previously to a 

 second gestation, as if the development of the young during tin- 

 Latter were arrested by a relative insufficiency of nourishment. In 

 some cases the period of gestation was half as long again as the 

 normal duration. 



Kirkham" says that with white mice where more than two young 



1 Williams. /..<. - />. 



- Allen (L. M.), ''Prolonged Gestation," Amer. ./""/. of <>l>*f<-t., vol. lv., I!o7. 

 3 Tessier, " Recherches sur la Duree de la Gestation, etc.," Mem. <!>' /' . !<-/,/. ,/,-x 

 >V ;,-, />.<, Paris, 1817. 



' Franck-Albrn ht-< ;.">ring, "Die Triichtigkeitsdauer," Tlii<-rnr.tli<-h<- <;>-l>u,'t- 



x/iff.; vol. iv., 1901. 



Pinanl. Article "Gestation," Richet's />///<////>> ,!, /'/<//.// ii<; vol. vii., 

 Paris, 190.-,. 



Kirkliam. "Tin- PKilun^.-d ( iestation Periofl in Suckling Mice," J/*"/. />>> . 

 vol. \i., 191<i ; "The Life of the White Mous.-." /'/-. Soe. /:'./>. ////. "/"/ J/-'/.. 

 vol. xvii . l!^o. Kirkliam and also Adlcr, writing earlier, stat- that tlif 

 iiiaiiiinai v glands exert an inhiliitoi \ influence ujjon the stimuli coming from 

 the blastula or from the corpus luteuni. (Adler, " Versuche mit ' Manimimiim 

 Pot-hl ' betreffend die Funktion der Briistdrii.se als innerli-h ><-xei iii.- 



<'i.i:aii.' ; Ma ,/,. M,;{. \V, /,., vol. lix., 1912.) That the gestation period in 

 suckling mice is lengthened had l>een previously noted by Daniel ("Gestation 

 in White Mire," ./,,,>,-. A'/y. /.<,!., vol. ix., 1910), whil*-' Miss Kintr i"-i(U 

 similar phenomena in white rats ///.,/. A'"//., vol. x\i\., l!)|: J , . 



