8 THE PHYSIOLOGY OF REPRODUCTION 



Some interesting observations have been recoiled by Ashworth 

 and Annandale 1 about the breeding habits of sea-anemones, 'nit- 

 species Saf/artia troglodytes and A<-{ini<i Mesembryanthemfttm, which 

 are very prolific in captivity, have been noticed to breed regularly 

 in the early spring. Actinin commences to produce young in the 

 beginning of February, and Sagartia about a month later. As a rule 

 the young are extruded in the early morning, and one individual 

 may repeat the process every morning for a number of weeks, 

 when the breeding season comes to an end. In one season, when 

 the aquaria were somewhat neglected, the specimens of Sayrti 

 produced fewer young than usual, and these were not extruded 

 until the beginning of April. Specimens of Actinia living in the 

 same aquaria were more prolific, but their breeding season was also 

 somewhat retarded. In the month of August two anemones of the 

 species Scgnrtia troglodytes were brought from Thorshavn in the 

 Fa-roes, and placed in the aquaria. In the following October both 

 of these produced several young ; while in April of the next year 

 one of them again gave birth, but only to a single anemone. It 

 seems probable that in this case the change of temperature or 

 environment had induced the anemones to breed at an unusual 

 season ; for it is unlikely that October is the normal period for 

 reproduction in the Fa-roes, as by this time the sea has already 

 begun to run high, and there would be a great risk of the young 

 anemones becoming destroyed, being unable to attach themselves. 



Ashworth has pointed out' 2 that in the coral A'cuin hii-l-xm/i, 

 which lives in the tropics, there is every evidence that spermatozoa 

 are discharged over a very considerable period, if not practically 

 throughout the whole year, whereas in the related form A 

 (/li/i/iifmn, of Northern Europe, the period during which the s 

 matoxoa are discharged is limited to about a month in the winter. 

 Ashworth remarks that the difference is probably due to the fact 

 that A'l'niti, living on reefs in the shallow waters of tropical seas, is 

 not subject to great variations in temperature and food-supply, while 

 with Ali-i/uiiiinii such variations are no doubt considerable. In a 

 similar way Miss Pratt; 1 who has studied the process of oogenesis in 

 Sarcophytum, ir<>/(>/>/it/fnin, and ScleropJiytum, concludes that tin- 

 sexually mature condition in these tropical genera extends over a 



and suggestive information on the factors which control breeding in plants 

 <J. Kid >s' work should be consulted. ( If 7//X- ///,/,< Entmetevmgt&nderungex 

 bet l\ll ;, 1!)03.) 



1 Ashworth and Annandale, "Observations on some Aged Specimens of 

 Sagartia troglodyte*, &nd on the 1 Miration of Life in Cu-lenterates," J'r<: A'o//. 

 >'-. Win., vol. \x\., 1904. 



- Ashworth, "Structure of X<'ni<i ///<-/-xn,//, :: V"'"'- /<""' -'/ '"'/ 

 vol. .\lii. 



3 Pratt, "On Some Alcyonidie," //<>/<///;"/''.< Cai/lim //</ //-/x, vol. iii. 



