480 DK. MAXWELL T. MASTERS ON 



met with in Japan, nevertheless have not hitherto been discovered 

 in any part of Japan — e. g. Sequoia. It is also at least possible, 

 assuming Japan to have been a distinct centre, that at some time 

 migration may have taken place principally westward to Asia, and 

 to a less extent eastward to the Pacific side of America. 



With reference to the fossil species of this order, it behoves me 

 to speak with great diffidence, inasmuch as 1 have made no spe- 

 cial study of them. Judging, however, from the great range of 

 variation in existing species, and the stages of growth they pass 

 through, it would seem that the data upon which the student of 

 fossil plants has often to deal must be peculiarly unsafe as guides 

 to the discrimination of species in this order. Where the different 

 stages or forms of growth exist, as they sometimes do, on the same 

 tree or shrub, as in the Chinese Juniper, there is no difficulty about 

 the matter ; but this fortuuate state of things is the exception 

 rather than the rule. Take, for instance, the numerous Japanese 

 forms of the Retinospora-groxxp. These forms belong to different 

 genera, are widely different one from another and from the perfect 

 tree ; and for the most part they preserve their characters without 

 change, at least under cultivation. The consequence is that they 

 are taken as so many distinct species by those who have not had the 

 opportunity of seeing the passage from the one to the other. The 

 student of fossil plants, meeting with analogous isolated forms, 

 would be almost certain to enumerate them all as separate and 

 distinct species ; the evidence before him would not suggest any 

 other course. The instance of Abies bifida and A.firma is another 

 case in point. The two stages represented by those names are so 

 different, the internal anatomical structure of the leaves and the 

 arrangement of the resin-canals so very distinct, that they have 

 been considered as belonging to separate species. Large culti- 

 vated specimens in our nurseries are so different that they are, 

 with very good reason, sold as separate species ; and the workmen 

 accustomed to handle them, and whose appreciation of the points 

 of difference between forms is often much keener than that of the 

 professed botanist, are apt to express the greatest astonishment 

 when told that A. bifida and A.firma are one and the same. The 

 evidence in support of this statement is given under the head of 

 A.firma. Such cases (and they are not infrequent in Conifers) 

 should make descriptive botanists pause before establishing new 

 species. 



Whatever caution may be deemed necessary as to the interpre- 



