220 swingle: merotypes 



these facts were first noticed, the persistent leaf-base of the peach 

 remains alive for a year or for two but finally dies and withers 

 away. In Maryland peach trees the petiole base lives through 

 the winter and separates when the buds start in the spring, leav- 

 ing a fresh green leaf-scar. 



The apple and its relatives do not share these specialized leaf 

 characters of the stone fruits. There is no joint above the attach- 

 ment of the stipules and basal section of the leaf falls off with the 

 rest. The stipules of the quinces are much closer to the base 

 of the leaf than those of the apple, and might be supposed to have 

 a separate attachment to the branches. But on "water shoots" 

 of Chinese quinces at San Antonio some of the stipules were of 

 very large size and had strongly dentate margins. In these cases 

 there could be no question regarding the attachment of the stipules 

 to the petiole. 



Another fact that may indicate greater complexity of leaf struc- 

 ture among the ancestors of the Amygdalaceae is the presence of 

 small oblong or spatulate leafy organs on the upper part of the 

 petiole, taking the place of nectaries. In some varieties of apri- 

 cots these small accessory blades are of frequent occurence. They 

 suggest the possibility that the nectaries of the petioles of Amygda- 

 laceae may correspond to the marginal glands of the blade and 

 may represent rudiments of divisions of compound leaves. If 

 this be true the petiole in this group may correspond to the rachis 

 of a compound leaf rather than to the more specialized petioles 

 of some of the simple-leaved families. 



BOTANY. — Merotypes as a means of multi-plying botanical types. 

 Walter T. Swingle Bureau of Plant Industry. 



Type specimens are now the most treasured possessions of 

 natural history museums. The type specimen of an organism 

 constitutes a fixed point in the taxonomic survey of the group of 

 individuals which make up the species, and while it may not be 

 typical of the latter in the ordinary English sense, it does at least 

 determine one form which must remain in the species no matter 

 how opinions may vary as to its limits. 



It is now generally held that only one specimen is to be regarded 



