1861.] Professor Huxley on the Development of Ani?nah. 3 1 5 



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WEEKLY EVENING MEETING, 



Friday, February 8, 1861. 



Sir Roderick I. Murchison, F.R.S. Vice-President, in the Chair. 



Professor T. H. Huxley, F.R.S. 

 On the Nature of the Earliest Stages of the Development of Animals, 



The lecturer commenced by giving a general description of the struc- 

 ture and singular properties of the animal organism, termed Pyrosoma 

 Giganteum, a specimen of which, taken by Capt. Callow in the 

 North Atlantic, had been forwarded to him by Admiral Fitzroy, in 

 the autumn of 1859. 



Not only had his investigations enabled the speaker to verify the 

 most important of the statements made in his memoir on Pyrosoma, 

 published in the Philosophical Transactions for 1851 ; but they had 

 revealed peculiarities in .the mode of reproduction of the animal, of 

 great interest from their bearing on some of the most difficult questions 

 of embryology. 



In order to render the importance of these new facts obvious, it 

 was necessary to premise a concise statement of our present knowledge 

 with regard to the early stages of animal development. To this end 



