REPRODUCTION 



377 



Figure 212. Section of 

 umbilical cord of a Fin 

 Whale foetus. Mote the two 

 veins, the two arteries, and 

 the urachus which lie embed- 

 ded in jelly-like connective 

 tissue. The amnion pearls 

 can be seen on the outer coat. 



of puppies and kittens which has to be bitten off by the mother. In 

 Cetaceans, the cord becomes strained the moment the snout has left the 

 mother's body, i.e. when the new whale is fully born. 



All biologists who have watched this process are agreed that it takes a 

 fairly long time for the after-birth - i.e. the placenta, the rest of the 

 umbilical cord and the foetal membranes - to be expelled. Sleptsov 

 mentions one and a half to two hours, James speaks of four hours, and 

 McBride and Kritzler (Marineland Aquarium) had, on one occasion, to 

 wait for ten hours after birth before the after-birth emerged. Occasionally 

 the umbilical cord fails to rupture, in which case it probably pulls the 

 placenta behind it, with fatal consequences for the calf, since the cow 

 generally fails to bite the cord off and the heavy placenta dragging 

 behind the calf prevents it from coming up for air. During July and 

 August, dead newly-born porpoises are quite often washed up on the 

 North Sea coast, their placenta attached to an imruptured cord. Though 

 it is by no means certain whether these animals choked to death or died 

 of other causes, it seems reasonable to assume - until the matter is investi- 

 gated further - that choking was responsible for some of the deaths at 

 least. 



In most terrestrial mammals, herbivores included, the mother generally 

 swallows the after-birth, probably so as not to allow the nest to become 

 fouled, or not to betray the presence of her ofTspring. Moreover, the after- 

 birth provides the mother with food, thus enabling her to stay with her 

 young instead of having to forage for prey the moment it is boi'n. It is also 

 thought that the placenta, in particular, contains certain substances which 

 stimulate lactation. In Cetaceans which cannot foul their nest, the after- 

 birth is abandoned, and the cow shows no interest in it at all, devoting 

 all her attention to the calf which must be persuaded to the surface at the 

 earliest possible moment. We have seen that young Bottlenoses in the 

 Marineland Aquarium were able to keep up with their mothers straight 

 after birth, that they surfaced within ten seconds of being born, or else 



