S6 THE PHYSIOLOGY OF REPRODUCTION 



in April, or sometimes as late as early May. A second litter of 

 moles may be , born later in the year, but this fact has not been 

 definitely proved.^ 



It would appear that in some Insectivores the prooestrura may be 

 comparatively severe, for in Twpaia javanica Stratz ^ has described a 

 "menstrual" blood-clot which contained pieces of desquamated 

 epithelium. 



Chbikoptera 



As will be explained more fully in a future chapter, some species 

 of bats appear to be exceptional in that the. season of oestrus does 

 not synchronise with the period of ovulation. It has been shown by 

 Benecke,* Eimer,* van Beneden,'"^ and Salvi, that whereas copulation 

 may occur in the autumn, the ova are not fertilised until after the 

 winter hibernation, the spermatozoa in the meantime lying dormant. 

 Salvi," however, describes the bats in the Grotta dell' Inferno, near 

 Sassari, as copulating also in the spring, but it is suggested that 

 coition at this season may only take place among those females which 

 have failed to become inseminated effectively in the previous autumn.'^ 

 It does not appear to be known whether the polyoestrous condition 

 ever 0C9urs in bats. 



It is stated that a "menstrual" (prooestrous) flow has been 

 observed in the flying fox (^Pteropus)? 



Primates 



Zf»mrs.-^ Among Lemuroids, Stratz^ has shown that in Tarsius 

 spedruvi there is a sanguineous prooestrous discharge almost as 

 concentrated as in monkeys. This is presumably followed by an 

 cestrous period. It is stated also that Tarsius experiences an . 

 uninterrupted series of dicestrous cycles (i.e. a condition of continuous 

 polyoBstrum) ; but that, whereas conception is possible at any time of 

 the year, breeding occurs more frequently in October and November 

 than at other seasons.^" 



1 Millais, loc. cit. See also Adams, " A Contribution to our Knowledge of 

 the Mole," Mmichester Lit. arid Phil. Soc. Mem., 1902. 



2 Stratz, Der gescUechtsreife Saiigethiereierstock, Haag, 1898. 



3 Benecke, "Ueber Eeifung und Befruchtung des Eies bei den Fleder- 

 mausen," Zool. Am., vol. ii., 1879. 



* Eimer, "Ueber die Fortpflanzung der Fledermause," Zool. Anz., vol. ii 

 1879. 



^ Van Beneden, "Observations sur la Maturation, la Fecondation, et la 

 Segmentation de I'oeuf chez les Cheiroptferes," Arch, de Biol., vol. i,, 1880. 



^ Salvi, " Osservazioni sopra I'Accoppiamento dei Chirotteri nostrani," Atti 

 della Societa Toscana di Scienze Natmrali, vol. xii., 1901. . 



' Duval, Etudes sur V JSmhryologie des Cheiropteres, Premifere Partie, Paris 



1899. ' 



' Wiltshire, loc. cit. " Stratz, loc. cit. i" Van Herwerden, loc, cit. 



