446 NOTICES OF THE MEETINGS [May 19, 
words are not the same, yet they are modifications by known de- 
velopmental laws of the same root. 
Now Von Bir has shewn that the study of development has a 
precisely similar bearing upon the question of the unity of organiza- 
tion of animals. He indicated, in his masterly essays published five 
and twenty years ago, that though the common plans of the adult 
forms of the great classes are not identical, yet they start in the course 
of their development from the same point. And the whole tendency 
of modern research is to confirm his conclusion. 
If then with the advantage of the great lapse of time and pro- 
gress of knowledge, we may presume to pronounce judgment where 
Cuvier and Geoffroy St. Hilaire were the litigants —it may be said 
that Geoffroy’s inspiration was true, but his mode of working it out 
false. An insect is not a vertebrate animal, nor are its legs free 
ribs. A cuttlefish is not a vertebrate animal doubled up. But 
there was a period in the development of each, when insect, cut- 
tlefish, and vertebrate were undistinguishable and had a Common 
Plan. 
The Lecturer concluded by remarking, that the existence of 
hotly controverted questions between men of knowledge, ability, and 
especially of honesty and earnestness of purpose, such as Cuvier and 
his rival were, is an opprobium to the science which they profess. 
He would feel deeply rewarded if he had produced in the minds of his 
hearers, the conviction that these two great men —friends as they 
were to one another —need not be set in scientific opposition ; that 
they were both true knights doing battle for science; but that as 
the old story runs, each came by his own road to a different side of 
the shield. [Ty 
WEEKLY EVENING MEETING, 
Friday, May 19. 
W. R. Grove, Esq., Q.C., F.R.S., Vice-President, in the Chair. 
Joun Tynvatt, Esq., Ph.D., F.R.S. 
PROFESSOR OF NATURAL PHILOSOPHY IN THE ROYAL INSTITUTION. 
On some Phenomena connected with the Motion of Liquids. 
Tur Lecturer commenced by referring to certain phenomena 
exhibited by liquids, and at variance with our commonly re- 
ceived notions as to their non-cohesive character. According 
to Donny, when the air has been as far as possible expelled 
