222 Mr Bles, On the breeding habits of Xenopus laevis Baud. 



elapsed since the last eggs were laid on the following morning. 

 Pairing took place on the nights of Feb. 28th, March 3rd and 

 March 5th and altogether between 400 and 500 eggs were laid. 



Oviposition is carried out in the following manner. The pair 

 swim about rapidly for a few minutes, then they stop and the 

 female clasps a leaf of a water-plant between her feet and the 

 egg which has been held in the cloacal tube is shot out against 

 the weed. Each time this occurs a spasm passes over the body of 

 the male, and most probably spermatozoa are then ejected, each 

 egg being fertilised separately. There can be no doubt that there 

 is nothing of the nature of a spermatophore and that fertilisation 

 takes place in the water. 



The egg when first laid has a strongly adhesive outer layer, 

 which makes it fast to the first foreign body it touches. Before 

 the tadpole hatches, which is 30 — 36 hours after spawning in 

 water at 22° — 24° C, this outer coat becomes hard and horny and 

 very elastic. The embryo has to squeeze itself out through a 

 narrow chink in this envelope. 



In most of the above remarks I have extended the observations 

 made by Mr J. M. Leslie 1 and there are only two important points 

 to note on which I differ from him, one is regarding the extent 

 of the nuptial markings on the arm of the male, and the other 

 concerns the croak, which he stated to be absent. 



It is noteworthy that these frogs bred after at least four years 

 of captivity and not at the time of spawning at the Cape, which 

 is in August. 



I have much pleasure in thanking Mr Lynch and the indoor 

 foreman at the Botanic Garden for their many kindnesses to me 

 during these experiments. 



On the Recovery of foliage Leaves from surgical Injuries. By 

 F. F. Blackman and Miss G. L. C. Matthaei. 



[Head 20 May 1901.] 



It has been found that if definite areas of certain leaves be 

 killed by heat or by physical means, the remaining sound tissues 

 divide actively and form an absciss-layer which surrounds the 

 dead cells and cuts out the area so that it drops away from the 

 leaf. Specimens were exhibited showing the stages of this process 

 which takes place with such precision that leaves may thus be 

 shaped to any desired form. 



1 "Notes on the Habits and Oviposition of Xenopus laevis," by J. M. Leslie, F.Z.S., 

 Proc. Zool. Soc. Lond., 1890, p. 69. 



