Among his predecessors, Pander spoke first of "Malpighi, 

 who in his 'Epistolary Dissertation on the Formation of the 

 Chicken in the Egg, ' . . . . has given us wonderful presenta- 

 tions accompanied by brief explanations." Pander gave no less 

 consideration to Haller's work, especially to two French 

 memoirs on the development of the heart, and to a Latin paper 

 on this subject. "However, with the greatest praise," Pander 

 discussed Wolff's wonderful observations which are partially 

 stated in the book THE THEORY OF GENERATION, and partially in 

 his treatise "On the Formation of the Intestines" presented in 

 the twelfth and thirteenth volumes of the COMMENTARIES of the 

 St. Petersburg Academy of Science. 13 j n regard to circulation 

 in the vessels and the movement of blood there, Pander referred 

 to Spallanzani' s "Features of Circulation" ("Dei fenomeni della 

 circilogione," 1773) . In concluding his review of the litera- 

 ture, Pander briefly stated: "It is impossible to ignore the 

 careful observations of the most famous master of graphs, 

 Tredern." 14 



The first paragraph of Pander's dissertation is devoted to 

 the earliest developmental stages of the incubated egg. On 

 the surface of the yolk and hanging in the egg albumin, Pander 

 saw the small whitish spot, the cicatrice, saying that "Dif- 

 ferent authors called it by different names (66), but nobody 

 tried to determine how it is situated, where it is located and 

 from where it originates. "15 Pander himself stated that the 

 yolk membrane near this spot is thin and transparent and that 

 egg cicatrices suitable for incubation are distinguished from 

 the formations found in nonfertilized eggs. In the latter the 

 spot is smaller, whiter, granulated, and not completely rounded 

 In fertilized eggs, the spot is larger in size, leaden-whitish 

 and entirely rounded. The surrounding yolk forms an intensive- 

 ly colored zone, and the spot itself is edged with a paler 

 border and has in the center a white spot. On lifting the yolk 

 membrane, Pander found that the spot is composed of one layer 

 of light granules and has the shape of a disk located between 

 the yolk and the yolk membrane. The central part of the disk 

 is attached to the lump underneath, to which the whiter color 



13. Ibid . , p. 16. 



14. Ibid ., p. 17. 



15. Ibid., pp. 18 - 19. 



245 



