After I finished my observations on the nervous 

 system of echinoderras and reported all the existed 

 to Mr. Delle-Kyaie, I learned from this scientist 

 that Mr. Van Beneden, a year before, had already 

 discovered traces of the nervous system in echinus, 

 information about which had appeared in L'INSTITUT. 

 Because I could never get the proper issue of this 

 journal, I should not be birred for not mentioning 

 Van Beneden' s observations . (p. 7) 



In all his works Krohn, with exceptional honesty and 

 modesty, mentioned the results of the work of his predeces- 

 sors, not fearing to recognize the superiority of foreign 

 observations over his own. 40 



No information was kept on personal events in Krohn 's 

 life. He was not connected in his work either with scientific 

 institutions or with universities. His life as a traveller- 

 naturalist hardly assisted the acquisition of a family of 

 his own. To his relatives Krohn superficially referred in a 

 letter to Johannes Muller:41 "After eight months absence, 

 during which I spent April and May in Santa Cruz in Tenerife, 

 I returned to Europe. The immediate cause for this was a 

 forthcoming meeting with close relatives, whom I had not 

 seen for some years" (p. 515). 



In the first period of scientific activity (up to 1846) 

 Krohn' s scientific interests were concentrated in the anatomy 

 of vertebrates (fish, amphibia, birds) and invertebrates 

 (coelenterates, annelids, arachnids, chaetognatha, molluscs, 

 bryozoa, crustaceans, echinoderms, tunicates) . Incidentally 

 to his morphological investigation, Krohn found parasites 

 in the venous sinuses of cuttlefish (apparently diciemid) and 

 described new species of pteropod and cephalopod molluscs. 



Zootomical and zoological investigations were continued by 

 Krohn, investigating the structure of protozoa, siphonophora, 



40. Concerning the budding of the complex ascidian, Krohn 

 wrote: "Mechnikov, with greater success than I, has 

 traced the gradual development of buds" (Krohn, "Uber 

 die Fortpflanzungsverhaltnisse bei den Botrylliden, " 

 ARCH. NATURGESCH., 35 (1869), pp. 190 - 196). 



41. ARCH. ANAT., PHYSIOL. (1856), pp. 515 - 522. 



56i 



