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 noteworth}' 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. 
[Read 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, ”byJ. M. Leslie, F.Z.S., 
Proc. Zool. Soc. Lond ., 1890, p. 69. 
