SECT. 3] AND EIGHTEENTH CENTURIES 181 



In 1722 Antoine Maitre-Jan published his book on the embryology 

 of the chick, the only one on this subject between Malpighi and 

 Haller. It was an admirable treatise, illustrated with many drawings 

 which, though not very beautiful, were as accurate as could be 

 expected at the time. Perhaps its most remarkable characteristic 

 is its almost complete freedom from all theory — Maitre-Jan says 

 hardly a word about generation in general, and is far from putting 

 forward a "system" in the usual eighteenth-century manner. He 

 contents himself with the recital of the known facts, including those 

 added by his own observations. He gives no references, and writes 

 in an extremely modern and unaffected style. 



The only traces of theoretical presupposition which can be found 

 in him are Cartesian, for he speaks of the activity of ferments in 

 blood-formation. He is an epigenesist, and long before Brooks, he gives 

 the right explanation of Malpighi's error, affirming that the hot 

 Italian summer was responsible for some development in Malpighi's 

 eggs before Malpighi examined them. Maitre-Jan's book must have 

 been accessible both to Buffon and Haller, so it is difficult to see why 

 they should have perpetuated Malpighi's mistake till nearly the end 

 of the century. 



In technique, Maitre-Jan was pre-eminent. He was the first 

 embryologist to make practical use of Boyle's suggestion regarding 

 "distilled spirits of vinegar" for hardening the embryo so that it 

 could be better dissected. He also used "weak spirits of vitriol"; 

 after treating blastoderms with it, he said, "I saw with pleasure an 

 infinity of little capillary vessels which had not appeared to be there 

 before". He made a few chemical experiments also, noting that 

 vinegar would coagulate egg-white, and estimating quantitatively 

 the difference in oil-content of different yolks — though for this he 

 gives no figures. 



His theory he relegated to an appendix entitled Objections sur 

 la generation des animaux par de petits vers. There were sixteen of 

 them, but the most cogent one was that, as little worms had been 

 found under the microscope in pond-water, vinegar, and all kinds 

 of liquids, there was no reason to suppose that those in the semen 

 were in any essential way connected with generation. For his time, 

 this argument was an excellent one, and was open to no demur 

 save on the ground of filtration experiments which had not yet been 

 made (see p. 215). 



