perceived by the weaker magnification," is controversial. 

 These words must not be considered as an expression of a 

 scornful attitude on Wolff's part to the microscope as an 

 instrument of scientific investigation. 4 Wolff apparently- 

 meant only that magnification by the microscope does not 

 always find in the embryo the preformed organism, because 

 the latter is not always present. Thus, Wolff declared in 

 the German THEORIE that "the seminal animals (spermatozoa) — 

 these are not the production of philosophy, but the result of 

 Leeuwenhoek's polished glass" (p. 73). Here the sharp polemics 

 are turned, of course, not to Leeuwenhoek's technical 

 achievement in improving the microscope, but to the idea of 

 animalculism, which supposes that in the spermatozoid, an 

 animal exists preformed. 



Wolff returned again to the question of whether it is 

 possible to confirm the existence of unperceptible substances. 

 His point of view is completely definite: the investigation 

 must take into consideration only that which can be perceived 

 and must judge the existence of substances by their 

 detectable manifestations. Wolff's idea is presented in the 

 following form: 



I can, for example, very easily prove that in my bag 

 there is no "fridrikhsdor"^ and no Dorida is present 

 now in my room. You easily see that these determined 

 substances are connected with determined manifestations, 

 which in conformity with their nature cannot remain 

 secret. The "fridrikhsdor" in my bag must be seen or 

 be felt, and if Dorida is now present, then other signs 

 of her presence must be available. 



Comparing the embryo after 28 and 36 hours of incubation, 

 Wolff discovered in the latter the beginning of the heart, in 

 the form of a tube. This tube has the form of a third of 

 a ring, still not pulsating and not connected with the arteries 

 and veins. He, with surprise, noticed that during the short 



4. Thus, apparently, S. L. Sobol was ready to consider in his 

 main work, ISTORIYA MIKROSKOPA I MIKROSKOPICHESKIKH 

 ISSLEDOVANII V ROSSII V XVIII VEKE (History of the 

 microscope and microscopical investigations in Russia in 

 the 18th century) , Moscow: Akademii Nauk, 1949. 



5. A golden coin. 



54 



