290 SUMMARY OF CURRENT RESEARCHES RELATING TO 



lung rudiment there occurs a considerable space. The lung rudiment in 

 Ceratodus is an unpaired outgrowth of the ventral wall of the gut close 

 to and on the right side of the median plane. It is quite distinct from 

 the relatively short gullet pockets occurring in the lateral wall, and 

 cannot be regarded as arising from gill pouches. 



Parental Care in Lophobranchs.* — Max Petersen has studied the 

 brood-pouch in Nerophis ophidion and Siphonostonia typhle. In the 

 former the eggs are found firmly attached in 2-3 longitudinal rows on 

 the ventral surface of the male, between the gills and the anus. They 

 are attached by a layer of mucus, which seems to be produced by the 

 epithelial cells of the male. Some eggs removed from their attachment 

 failed to develop, but there is no definite evidence that the attach- 

 ment has any respiratory or nutritive significance. The egg-laying in 

 Nerophifi begins in the first half of May, and ends in July. 



In Siphonostonia, the pouch begins to be formed (at Greifswald) early 

 in May ; the eggs are liberated from the last third of May to the middle 

 of June ; most of the embryos hatch in July. The retrogressive changes 

 in the pouch are completed by about the middle of October. A series of 

 stages showing the development of the pouch from two folds of the 

 integument is carefully described. The author believes that the seminal 

 fluid liberated into the water finds its way into the pouch where fertili- 

 sation takes place. But his observations are not conclusive. After 

 fertilisation the margins of the pouch-valves are apposed, and the pouch 

 is shut, and there is a peculiar internal folding of the epithelium. The 

 pouch consists of (1) the external epithelium ; (2) a two-layered stratum 

 of connective tissue with numerous blood-vessels ; and (3) an internal 

 epithelium. In the filled pouch there are noteworthy changes in the 

 two inner layers. There must be diffusion of oxygen from the paternal 

 blood-vessels to the inclosed eggs, and Petersen thinks that there is also 

 a nutritive connection. In the retrogressive changes which lead to the 

 disappearance of the pouch, phagocytes play an important if not an 

 exclusive role. 



Effect of Radium on Scyllium embryos.f— Jan Tur has experi- 

 mented with eml)ryos of ScylUum ca/ticula, and finds that radium salts 

 exert what he terms a local and " teratogenetic electivity." They pro- 

 voked in every case identical malformations, which were confined to 

 axial parts. Longitudinal growth was arrested. The nervous system 

 underwent involution, becoming a simple ectodermic plate which con- 

 sisted of a mass of rounded cells whose protoplasm showed necrotic dis- 

 integration. The blastoderm outside the embryo remained normal ; 

 radium effects were most marked on embryonic elements poor in vitellus. 



Text-Book of Teratology. J — Ernst Schwalbe has completed the 

 second part of his morphology of abnormalities in man and animals. 

 It deals with the various forms of duplicities in development. 



* Zool. Jahrb., xxiv. (1906) pp. 265-306 (1 pi. and 15 figs.). 



t Arch. Zool. Exper., Notes et Revue, No. 2, xxxv, (1906) pp. xxxix.-xlviii. 

 <6 figs.), 



J Die Morphologic der Missbildungeu des Menschen und der Tiere. II. Teil. 

 Die Doppelbildungen. Jena, 1907, 2 pis. and 39J: tigs. See also Anat. Auzeig., 

 XXX. (1907) pp. 31-2. 



