38 THOMAS HENRY HUXLEY 



of Rreslau, the commencement of that general recogni- 

 tion of his scientific eminence by foreign countries which 

 was afterwards manifested in so large a measure. 



The scientific work for 1857 includes the following 

 memoirs : — 



1. "Description of a New Crustacean (Pygocephalus 

 Cooperi, Huxley) from the Coal Measures " (Q. J. Geol. 

 Soc, xiii, 1857, pp. 363-9. Sci. Mem., i, XLiii, 

 p. 463). 



2. " On Dysteria; a New Genus of Infusoria" (Q. J. 

 Micros. Sci., v, 1857, PP- 78-82. Sci. Mem., i, xliv, 

 p. 471).' — This is an account of a marine animalcule, dis- 

 covered by Dr. Dyster at Tenby. 



3. " Review of Dr. Hannover's Memoir : ' Ueber die 

 Entwickelung und den Bau des Saugethierzahns '" (op. 

 cit., V, 1857, pp. 166-71. Sci. Mem., i, xlv, p. 476). 

 — This is a critical review of a research on the structure 

 and especially on the development of mammalian teeth. 



4. " On the Agamic Reproduction and Morphology 

 of Aphis " (Trans. Linn. Soc, xxii, 1858, pp. 193-220, 

 221-36. Read November 5, 1857. ^ci. Mem., ii, 11, 

 p. 26). — This classical memoir deals in detail with the 

 structure and life-histories of Aphides {vide infra). Apart 

 from the descriptive work it embodies generalizations of 

 high value, and the influence of Von Baer is clearly trace- 

 able in the emphasis laid upon embryological evidence. 



During 1858 the usual lectures were given, including 

 a course on the " Principles of Biology " at the Royal 

 Institution, the last of a triennial series delivered in the 

 capacity of Fullerian Professor. A Friday Evening Dis- 

 course ''On the Phenomena of Gemmation" was de- 

 livered at this Institution on May 21. This dealt with 

 the extraordinary life-histories of Aphides, familiarly 

 known as "plant lice" or "green fly," in which sexual 



