LINIfEAN SOCIETY OF LONDOX, II 



2. " The CEconomy of Ichneumon manifestator, Marsbam." By 



C. MoRLEY, F.E.S. (Communicated by E, A. Cockayne, 

 F.L.S.) 



3. " The Polyzoa of Madeira." By the Eev. Canon Norman, 



M.A., F.E.S., F.L.S. 



February ISth, 1909. 



Dr. D. H. ScoxT, F.E.S., President, in the Chair ; afterwards 

 Lt.-Col. Pbain, C.I.E., F.E.S., A'ice-President. 



The Minutes of the General Meeting of the 4th February, 1909, 

 were read and confirmed. 



Miss Helen Stuart Chambers, B.Sc, was admitted a Fellow. 



Mr. Alexander James Gibson, Mr. Edward James Salisbury, 

 B.Sc, and Miss Marie Charlotte Carmiehael Stopes, D.Sc. (Lond.), 

 Ph.D. (Munich), were proposed as Fellows. 



Mr. David Eeekie was elected a Fellow. 



The President announced that two vacancies existed in the list 

 of Foreign Members, caused by the deaths of Prof. Alfred Giard 

 and Prof. Karl Mobius. 



The President then left the Chair, and was succeeded by Lt.-Col. 

 Prain. 



A discussion on " Alternation of Generations in Plants " was 

 opened by Dr. William H. Lang, M.B., D.Sc. After some intro- 

 ductory remarks and reference to some examples of well-marked 

 alternation of generations, and the nuclear difference between the 

 two generations, the Author adduced the ontogeny of organisms 

 without alternation of generations ; the concept of a specific cell 

 corresponding to each specific form. The concept of the specific 

 cell must be applied to organisms with alternation : the bodies of 

 the two alternating iudividuals in the life-history may be similar 

 or dissimilar. 



Two alternative explanations are open as to the differences 

 between the two generations in the complete life-history : 



(a) that the differences are due to the different state of the 

 specific cell in the spore and zygote respectively ; 



(6) that they are due to different environmental conditions 

 acting on equivalent germ-cells. 



