186 THE PHYSIOLOGY OF REPRODUCTION 



RoUinat/ in snakes belonging to the species Tropidonotus 

 viperinus the females are usually inseminated in the autumn, 

 whereas the eggs are not laid until the beginning of the following 

 summer. Also in the case of the spotted viviparous salamander 

 (Salamander maculosa), after the birth of the young, which occurs 

 about the month of May, a new batch of ova pass into the 

 oviducts and are fertihsed (prior to the commencement of the 

 sexual season) by spermatozoa which were introduced in the 

 July of the previous year, and thereafter stored in the uterus.^ 

 It is obvious that in both these cases the spermatozoa retain 

 their vitaHty in the female for periods of many months. 



In animals hke the earthworm, in which the spermatozoa 

 are stored in special reservoirs known as spermathecae, it is 

 probable that they retain their vitahty for long periods. Lang ^ 

 has shown that the sperms may live for three years in the 

 vesiculse seminales of snails. 



The extreme longevity possessed by the male cells of some 

 insects is still more remarkable. Von Siebold * states that 

 the spermatozoa of bees may survive for four or five years. 

 Moreover, queen ants have been known to lay fertile ova 

 thirteen years after the last intercourse with a male. 



1 KoUinat, " Sur FAccouplement des Ophidiens a la Fin de I'Ete et au 

 Commencement de I'Automne," Bull. Zool. Soc. France, vol. xxiii., 1898. 



' Sedgwick, Student's Text-Book of Zoology, vol. ii. , London, 1905. 



^ Lang, " tjber Vorversuche zu Untersuohungen iiber die Varietaten- 

 bildungen von Helix hortenaia Miiller and Helix nemoralia L.," Featachr. zum 

 aiebz 'gaten Oeburtatage von Emat Haeckel, Jena, 1904. 



* Von Siebold, " Fernere Beobaohtungeu iiber die Spermatozoon Wirbel- 

 loser Tiere," MUller'a Archiv, 1837. 



