From the above it can be seen that Nordmann's main 

 attention was to the relatively late stages of embryonic 

 development, while he investigated the process of division 

 of Tergipes only extremely incompletely. 



The brief discussion of the works of van Beneden, 

 Loven and Nordmann on the embryology of molluscs demonstrated 

 the level of knowledge in this sphere at that time. When 

 the development of molluscs was studied by the Russian 

 embryologist N. A. Warnek, his work can be unconditionally 

 called classical (131). Warnek's scientific activity, unfor- 

 tunately, was brief and was cut short by external circumstances, 



Nikolai Aleksandrovich Warnek was born in 1821. When he 

 was eighteen years old he entered the faculty of law at 

 Petersburg University, but in the same year he transferred 

 to a department of the faculty of philosophy. During his years 

 of study, Warnek received in 1843 the gold medal for his 

 "Process of Moulting of External Tegmens and Formation of 

 Millstone in the Ordinary River Crayfish." In 1846 he graduated 

 from the university with a candidate's degree, and for three 

 years he taught botany and zoology in Gorn Institute. Warnek 

 received his master of science degree for his work on the 

 structure and function of the crayfish liver^l and in 1849 

 he started reading lectures to naturalists and medical men 

 in comparative anatomy and physiology in Moscow University, 

 first as junior scientific assistant and then as extraordinary 

 professor (from 1852) . In 1848 Warnek wrote the vast work 

 "On the Formation and the Development of the Embryo in the 

 Gastropodan Molluscs," which was published two years later 

 in the BULLETIN OF THE MOSCOW SOCIETY OF NATURAL- 

 ISTS; 22 a summary of this work was published abroad under 



21. N. A. Warnek, "On the Liver of River Crayfish in 

 Anatomical and Physiological Relations" (SPb., 1847), 

 40 pp. 



22. warnek, "Ober die Bildung und Entwickelung des Embryos 

 bei Gasteropoden," BULL. SOC . NATUR . MOSCOW, 23 



(1850) , pp. 90 - 194. 



537 



