192 EMBRYOLOGY IN THE SEVENTEENTH [pt. ii 



Haller went further than Schurig, in that he usually gave an opinion 

 of his own after summarising those of other people, but his views were 

 by no means always enlightened, and the atmosphere of Buffon is, 

 on the whole, more congenial to us than that of Haller. Haller, 

 for example, believed that the amniotic liquid had nutritious pro- 

 perties, and that the nutrition of the embryo in mammalia was 

 accomplished first of^ all per os and afterwards per umbilicum. He denied 

 that the placenta had any respiratory function, and, indeed, his 

 whole teaching on respiration was retrograde. He mentions, how- 

 ever, an experiment of Nicolas Lemery's, in which it had been 

 found that indigo would penetrate the shell of a developing hen's 

 tgg from the outside. Consequently, air might do so too, and 

 Vallisneri had shown that, if an egg was placed in boiled water under 

 an air-pump, the air inside would rush out through the shell and 

 appear in the form of bubbles. 



Haller was much more progressive in holding the origin of the 

 amniotic liquid (according to him a subject of extraordinary diffi- 

 culty — " solutionem non promittam'") to be a transudation from the 

 maternal blood-vessels. He followed Noortwyck in asserting the 

 separateness of the maternal and foetal circulations in mammalia. 

 He opposed the existence of eggs in vivipara — "We may conclude 

 from all this", he said, "that the ovarian vesicles are not eggs and 

 that they do not contain the rudiments of the new animal". But he 

 accepted it in the restricted sense that the embryonic membranes 

 resembled an egg, thus: "If we call an egg a hollow membranous 

 pocket full of a humour in which the embryo swims, we may admit 

 the opinion of the older authors who derive all animals from eggs 

 with the exception of the tiny simple animals of which we have 

 already spoken. It was in this sense that Aristotle and Empedocles 

 before him, said that even trees were oviparous. This has also been 

 confirmed by the experiments of Harvey on insects, fishes, birds, and 

 quadrupeds". 



Haller's most original work was in connection with the growth- 

 rate of the embryo ; here he struck out, for once, into entirely new 

 country. "The growth of the embryo in the uterus of the mother is 

 almost unbelieveably rapid. We do not know what its size is at the 

 moment of its formation, but it is certainly so small that it cannot 

 be seen even with the aid of the best microscopes, and it reaches in 

 nine months the weight of ten or twelve pounds. In order to clear 



