SECT. 3] AND EIGHTEENTH CENTURIES 211 



the statues in certain gardens which could be made to perform un- 

 expected functions by the pressure of a manipulator's foot on a 

 pedal, but these instances were all artificially constructed mechanical 

 devices, whereas the Arbor Dianae was a natural phenomenon quite 

 unexplained by the chemists of the time, and the lineal forerunner 

 of Lillie's artificial nerve, and Rhumbler's drop of chloroform. We 

 know now that its formation is a simpler process than anything 

 which occurs in the developing embryo, but the course of research has 

 made it undeniably clear that the same forces which operate in the 

 formation of the Arbor Dianae are at work also in the developing 

 embryo. To this extent Maupertuis is abundantly justified, and 

 Driesch's comments on him are not in agreement with the facts. 



"Doubtless many other productions of a like kind will be found", 

 Maupertuis goes on, "if they are looked for or perhaps if they are 

 looked for less. And although they seem to be less organised than 

 the body of most animals, may they not depend on the same mechanics 

 and on similar laws? Will the ordinary laws of motion suffice, or 

 must we have recourse to new forces? These forces, incomprehensible 

 as they are, appear to have penetrated even into the Academy of 

 Sciences at Paris, that institution where so many opinions are weighed 

 and so few admitted." Maupertuis goes on to speak of the contem- 

 porary deliberations on the subject of attraction. "Ghymistry", he 

 says, "has felt the necessity of adopting this conception and attractive 

 force is nowadays admitted by the most famous chymists who have 

 carried the use of it far beyond the point which the astronomers 

 had reached. If this force exists in nature, why should it not take 

 part in the formation of animals?" Maupertuis was thus an epi- 

 genesist and a mechanist at the same time. His opinions have an 

 extremely modern ring, and his only retrograde step was in suggesting 

 that the spermatic animals had nothing else to do except to mix the 

 two seeds by swimming about in them. But that legacy of ovism 

 was common all through the eighteenth century, and thirty years 

 later Alexander Hamilton could say, "From the discovery of Animal- 

 cula in semine masculino by Leeuwenhock's Glasses, a new Theory was 

 adopted which is not yet entirely exploded". 



But the real middle point and fulcrum of the whole period lay in 

 the controversy between von Haller and Caspar Friedrich Wolflf, the 

 former at Gottingen and the latter at St Petersburg in the Academy 

 of the Empress Catherine. Kirchhoflf has described this polemic. 



14-2 



