424 Ganong . — The Comparative Morphology of 
and, if so, whether these shapes are the result of adaptation to 
similar conditions, or are determined by the working back of 
adaptive characters of the adults, or are due to some other 
cause. 
3. To find whether the young stages show features indicating 
anything as to the phylogeny of the genera. 
4. To find whatever else of interest might come out of a 
minute study of the young stages of this highly specialized 
family. 
Historical. 
Although there are many references to the germination and 
the seedlings of Cactaceae in systematic works treating of 
that family, as well as in other works of a morphological or 
ecological character, nevertheless no comparative study of the 
young stages has yet been attempted. It is still nearly as 
true as it was in 1858, when Labouret wrote: ‘ Les faits 
relatifs a la germination sont incompletement observes.’ 
Doubtless there are two reasons why this family, of such 
unusual morphological and ecological interest, has been 
neglected in this respect : first, the great difficulty of obtaining 
authentic seeds, and the considerable difficulty of raising 
them ; and second, the widely spread opinion, distinctly 
formulated by Pfeiffer, that the seedlings have no taxonomic 
value. Pfeiffer in 1837 wrote upon this subject as follows:— 
‘ Diese Beobachtungen lieferten mir den Beweis, dass die 
Keimung bei alien Cacteen, welche keine wahren Blatter 
haben, sehr ahnlich ist, und dass die Gestalt ihrer Cotyledonen 
keinen Gattungscharakter abgeben kann. Denn : 
(1) Ist dieselbe bei alien Mammillarien und Melocacten 
ganz gleich, wie ich bereits an einer grossen Menge von Arten 
beobachtet habe ; 
(2) Die Form derselben bei Echin. ingens unterscheidet 
sich aufifallend von der der ubrigen bekannten Echinocacten ; 
(3) Unter den j ungen Pflanzchen von Echin . robustus , von 
welchen ich eine ziemlich betrachtliche Menge besass, war die 
grosste Verschiedenheit der Gestalt, weshalb ich auch drei 
