25 [ 1-20 ] 



fossil shells, made from the diflevent tertiary beds in ditl'eront latitudes from 

 Maine to Florida, judiciously kept apart, would no doubt in time atlbrd 

 as precise documents for ascertaining the mean annual temperature of tbese 

 shores during the difTerent periods of the tertiory times, as a series of 

 thermometric observations. The person intrusted with the collection of 

 these materials should of course know the difference between the suc- 

 cessive beds of the tertiary deposites, and also the importance of never 

 mixing fossils from diflerent beds. Nothing would contribute more 

 directly to advance the solution of this problem than to obtain fiom the 

 superintendent of the United States coast survey some soundings and 

 dredgings at different depths, as the shells which live about low-water 

 mark are very ditlerent from those which occur successively at dilferent 

 depths, and such collections would contribute to establish the ratio of in- 

 fluence which climate has upon living beings. Species which are found 

 near the shores at a given point occurring also at various depths further 

 south, it is plain how important it would be to ascertain minutely their dis- 

 tribution in both directions horizontally and vertically. Such collections 

 should be extended to the classes of corals and echinodermS; including 

 in the latter the star fishes and sea urchins. 



"The other collection to which 1 call your attention- is a series of em- 

 bryos and young animals. There is no nuiseum at present in which 

 there is anything like a collection of this kind, as it should be every- 

 where, since the importance of embryology has been fully appreciated. 

 Taking care that such series be put up in the Smithsonian Institution, 

 wouldat once give to the collections of that establishment the stamp of 

 a true progressive scientific museum, even if it was confined to but few 

 branches. Embryonic collections can be made with a two fold object: 

 first, with a view of tracing the mode of formation and successive changes 

 of organs, constituting anatomical and physiological embryology; second, 

 with a view of comparing the ch.inges of forms which young animals 

 undergo ^fith the permanent forms of others similar to them, constituting 

 zoological embryology. To contribute to the progress of both these 

 branches of embryology, distinct collections should be made and kept as 

 distinct as our zoological and anatomical collections generally are. iMy 

 idea is, that an anatomical museum oi preparatmis from embryos and 

 young animals of all classes should be made at the same time as a zoolog- 

 ical museum of young in all ages and stages of growth, preserved whole. 

 Havin<^ but recently called attention to the miportance there is in compar- 

 ing the different stages of growth of all animals in order to ascertain thei 

 true relative position in a natural system, there is no pssil)ility at present 

 of appreciating the full value which such a collection will have lor the 

 future Every day I feel the want of it, and hundreds of questions, 

 which' arise constantly since the idea has been started, cannot be settled, 

 simply because there are no materials at hand anywhere for comparison. 



an oilier coiiecuuijo, cici 111*-- '"•^— -- i - i^„„,^,i u:„ 



in advance of all similar establishments so long as ^^"^''^Jf;"^^^'^^^ 

 attention to it. The expenses wonld not be very S'-^^'f Vo n te S eu' 

 series made from the most common ^"'"^^^'^ ^^''^^^'^,,':^ ^.^j^^^^^u''^^^^ 

 I can but repeat what 1 have said more than once, that the best chance 



