planula Velagia, while not settling on the bottom and not 

 transformed into scyphistomae, forms on the edges of the 

 mouth orifice processes, later becoming part of Ephyra 

 (Figure 43, B and C) with marginal sensory bodies. The 

 citation of this discovery can be found either in later 

 investigators of the embryology of medusae (for example, 

 KovalevskySl and Mechnikov (134)], or in textbooks. 52 ^ 



In 1861, during his residence in Nice, Krohn observed 

 the reproduction and development of hydromedusa Eleutheria , 53 

 The ova arise between ecto- and endoderm and there they 

 develop into the larval stage of larva. Ectoderm, covering 

 the embryonic chambers, swells into hillocks, which sub- 

 sequently break and release young. The larvae are considered 

 typical planulae and are subjected to the same transformation 

 as in the planula Cladonema. 



The budding occurs not only in asexual, but also in 

 completely differentiated bisexually related individuals. 

 Krohn described the process of budding, and noticed that the 

 budding begins in very young individuals, which are still not 

 completely separated from the maternal individual. 



51. A. O. Kovalevsky, "Observations on the development 



of Coelenterata," IZV. OBSHCH . LYUBIT. ESTESTV. 

 ANTROP. I ETNOGRAFII, 10 (1874), vyp. 2, pp. 1 - 

 pp. 1 - 36. To the work of Krohn there is reference 

 on p. 7. ^ 



52. K. N. Davydov, TRAITE D 'EMBRYOLOGIE COMPARES 

 DES INVERTEBRES (1928), p. 78. The drawings given 

 by Davydov (Figure 36) illustrating the development 

 of Velagia were taken by him from the work of Delap, 

 published more than fifty years after Krohn' s. They 

 are not a bit better than Krohn ' s drawings . 



53. A. Krohn, "Beobachtungen iiber den Bau und die 

 Fortpf lanzung der Eleutheria Quatref. , " ARCH . 

 NATURG., 27 (1861), 1, pp. 157 - 170. 



570 



