132 



REPORT 1860. 



The author then briefly entered into the general question of treatment to be pur- 

 sued, both for the parent and child, under the circumstances detailed. 



On Asiatic Cholera. By Sir Charles Gray. 



A Word on Embryology, ivith reference to the mutual relations of the Sub- 

 kingdoms of Animals. By J. Re ay Greene, B.A., Professor of Natural 

 History in the Queens College, Cork. 



In a communication bearing the above title, the author endeavoured to explain 

 that any real improvements in the arrangement of the animal kingdom which have 

 been made since the time of Cuvier accorded well with the corresponding advances 

 of comparative embryology. Thus only, indeed, were they shown to be true ; for 

 the method of gradations, whatever might be its value in suggesting affinities, 

 could not, of itself, be deemed sufficient to prove them ; while its exclusive employ- 

 ment had already, in too many cases, engendered errors, the further multiplication 

 of which coidd alone be kept in check by a continual appeal to the test of develop- 

 ment. From this point of view, the mutual relations of the five sub-kingdoms of 

 animals appear as in the accompanying analytical Table : — 



THE ANIMAL KINGDOM. 



The organism does not exhibit a 



division into true layers. 

 Subkingdom 1. PROTOZOA. 



A blastoderm is formed, which 

 divides into inner and outer 

 layers. 



j_ 



The two layers of the blastoderm 

 undergo no further funda- 

 mental differentiation. There 

 is no distinction into neural 

 and haemal regions. 

 Subkingdom 2. CCELENTERATA. 



The blastodermal layers become 

 further differentiated. The 

 organism exhibits neural and 

 haginal regions. 



The haemal region is first deve- 

 loped. There is no segmenta- 

 tion of the blastoderm. 

 Subkingdom 3. MOLLUSCA. 



The neural region is first deve- 

 loped. 



The blastoderm may become an- 

 tero-posteriorly segmented, but 

 there is no formation of pri- 

 mitive groove, dorsal and vis- 

 ceral plates*. 



Subkingdom 4. ANNULOSA. 



The blastoderm divides into so- 

 matomes. A primitive groove, 

 dorsal and visceral plates are 

 formed. 

 Subkingdom 5. VERTEBRATA. 



The generalizations here expressed may, to a certain extent, be regarded as co- 

 rollaries from the well-known proposition of J. F. Meckel : — d. h. das hohere Thier in 

 seiner Entwickelung dem AVesentlichen nach die miter ihm stehenden, bleibenden 

 Stupen durchlauft, wodurch also die periodischen und Classenverscheidenheiten 

 auf einander zuriiekgefukrt werdenf. For a Vertebrate ovum, before segmentation, 

 differs but little, essentially, from an astomatous Protozoon. At a later stage, 

 when the division of the blastoderm into serous and mucous lavers has just taken 

 place, it admits of easy comparison with the permanent forms of Calenterata, the 

 simpler organisms of this group being little more than double-walled sacs of peculiar 

 form, with one extremity open for the purpose of alimentation. 



* This proposition is stated and commented on by Professor Huxley in his recent menaoir 

 " On the Agamic Reproduction and Morphology of Aphis." See especially § 5 of the same 

 paper, entitled " The Einbryogeny of the Articulata, Mollusca, and Vertebrata compared" 

 (Linn. Trans, vol. xxii.). 



t System der vergleichenden Anatoinie, Erster Theil, p. 396. 



