270 M. Otto Hahn on Eozoon canadense. 



types whose earlier increase takes place upon some much more 

 definite plan. After what fashion the earliest development of 

 Eozoon took place we have at present no knowledge whatever ; 

 but in a young specimen which has been recently discovered, it 

 is obvious that each successive ' storey ' of chambers was 

 limited by the closing-in of the shelly layer at its edges, so as 

 to give to the entire fabric a definite form closely resembling 

 that of a straightened PeneropUs. Thus it is obvious that 

 the chief peculiarity of Eozoon lay in its capacity of inde- 

 finite extension ; so that any single organism might attain 

 a size comparable to that of a massive coral. Now this, it will 

 be observed, is simply due to the fact that its increase by gem- 

 mation takes place continuously ; the new segments succes- 

 sively budded-ofF remaining in connection with the original 

 stock, instead of detaching themselves from it, as in Forami- 

 nifera generally. Thus the little Olohigerina forms a shell 

 of which the number of chambers never seems to increase be- 

 yond <ew, any additional segments detaching themselves so as 

 to form separate shells ; but by the repetition of this multi- 

 plication the sea-bottom of lai-ge areas of the Atlantic Ocean at 

 the present time has come to be covered with accumulations of 

 Glohigerince^ which, if fossilized, would form beds of limestone 

 not less massive than those which have had their origin in the 

 growth of Eozoon. The difference between the two modes of 

 increase may be compared to the difference between a plant 

 and a tree. For in the plant the individual organism never 

 attains any considerable size, its extension by gemmation being 

 limited ; though the aggregation of individuals produced by 

 the detachment of its buds (as in a potato-field) may give 

 rise to a mass of vegetation as great as that formed in the 

 largest tree by the continuous putting forth of new buds." 



III. 



I commenced my investigations on three undoubtedly true 

 Canadian Serpentine limestones : — 



I. A specimen for which I am indebted to the kindness of 

 Professor Hochstetter of Vienna. It came from Carpenter 

 himself, and still bears his ticket. It is 95 millims. long 

 and 50 millims. broad. It may be divided into three layers : — 



1. Dolomite, 1-25 millims. ; 2, pure pale-green noble ser- 

 pentine (ophite), 25-35 millims. ; 3, broad bands of limestone 

 alternating with bands of serpentine 1 millim. broad, 35-55 

 millims. ; then follows a granular formation. 



From all the parts of the stone thin slices were taken. 

 Carpenter regards layer 1 as the base. 



