370 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The internal mass becomes divided into two sets of cells — the enteric 

 and ovarian. The former becomes differentiated into the stomach and 

 pharynx, and from the latter the endostyle soon becomes developed. 

 The nervous system commences as a thickening of the ectoderm, which 

 gradually becomes converted into an independent lens-shaped body, 

 the ganglion. Within this ganglion a lumen arises which enters into 

 connection with the lumen of the pharynx, in such a way that an 

 outgrowth of the pharynx is directed towards the ganglion ; this is the 

 so-called hypophysis of the Tunicata. The nerve-ganglion grows out 

 and forms a nerve-cord. 



The author's observations on the development of the gills were not 

 very complete, but he has been able to see that the cloaca forms two 

 lateral outgrowths which bend round the intestine and become applied 

 to the pharynx ; the neighbouring cells of the latter grow rapidly in 

 size and form special groups ; where these groups are formed open- 

 ings appear — the rudiments of the future gills. The mesoderm 

 appear to have no other function in Anchinia than that of forming five 

 muscular bands. 



The ovarian cells, after having attained a certain size, undergo 

 absorption ; from them there appear to arise new cells, each of which 

 has a large nucleus and soon becomes divided ; the function of these is 

 very problematical, but we have at present no right to regard it as 

 being renal. After some further observations on the germinal cells, 

 Korotneff passes to a discussion of the significance of the phenomena. 



He commences by pointing out that the maternal organism to which 

 the outgrowth and buds belong is completely unknown. We must, 

 therefore, in any further discussion of the question, base ourselves on 

 the analogy of the allied Doliolum. If this be justifiable, then we may 

 suppose that the unknown mother had a rosette-shaped organ from 

 which the primitive buds became separated ; these are the parts which 

 have given rise to the buds here described. The forms observed by 

 Barrels and Kowalevsky were sexual, those seen by Korotneff had 

 the genital organs reduced, and indeed only ovaries were detected by 

 him. It would seem, then, that the maternal organism is of the second 

 asexual generation, and we have then the following alternation. The 

 problematical asexual generation which possesses a rosette-shaped 

 organ, produces from the primitive buds special buds which are fixed 

 on the outgrowth. On this follows a series of similar buds, which 

 develope parthenogenetically until at last some of the buds give rise 

 to sexual organs. These last, by sexual means, give rise to the first 

 problematic individual. The case is complicated by the extension of 

 the asexual stages, and is analogous to what obtains among Aphides. 



The most remarkable of all the phenomena in the development of 

 AncMnia is the change which has taken place in the relation of the 

 organs to the germinal layers. The pharynx is developed from the 

 endoderm, and the same layer gives rise to the heart. How are these 

 very remarkable facts to be explained ? We must either suppose that 

 the germinal layers of the organism derived from the ovum are not 

 homologous with those here described, or that the germinal layers 

 have not, in the development of the different organs, the special 

 significance that has hitherto been attributed to them. 



