222 NATURAL SCIENCE. April, 



Mr. Henry Seebohm has recently issued a pamphlet dealing with 

 the classification of birds and supplementary to his previously 

 published work on that subject. In this place we cannot follow him 

 into the details of his scheme. The interesting nature of his work 

 will certainly insure attention from many naturalists, and those who 

 know about birds will object and criticise abundantly. 



For, as Mr. Seebohm admits, all the classifications of birds are 

 as yet largely matters of opinion. " Every attempt," he writes, " to 

 discover an ideal classification has hitherto been an absolute failure ; 

 and it can almost be proved that it involves a mathematical impossi- 

 bility, unless we admit that a primitive character may be independently 

 modified in a special direction by two distantly related families under 

 the influence of similar causes, and also that the influence of other 

 causes may afterwards produce a reversion to the primitive character 

 in some of the descendants. This admission is almost tantamount to 

 a confession that the attempt to arrive at finality in the classification 

 of birds is hopeless." 



It appears as if there were here some opening for the doctrine of 

 positions of organic stability recently expounded by Mr. Bateson. 

 Upon this theory, the characters of an animal, or some of them, 

 are bound together in some kind of inevitable correlation. If a change 

 occur, it is a sudden change to an adjacent position of organic 

 stability, and in the new position there is a kaleidoscopic change in 

 all the associated characters. Mr. Bateson apparently believes that 

 these adjacent positions of stability are so fixed that the same species 

 in two localities might give rise to the same other species ; that is to 

 say, at two places separated in space from each other some of the 

 members of a species might shift to the same adjacent position of 

 organic stability under the stimulus of the same external agencies. 

 In a group of animals so closely allied as birds it would not be 

 surprising to find, if the theory be true, that the same set of 

 characters appeared and reappeared more than once. But to prove 

 or disprove this, or indeed to proceed further with the unsatisfactory 

 classification of birds, still more anatomical knowledge is wanted. 



Our own opinion is that in this case, as in the case of Professor 

 Weldon's crabs, the study of correlations must be proceeded with 

 before any great advance in biological theory will be gained. The 

 animal body is in the first place a physiological unit, and investiga- 

 tions into the variations of parts of it, whether these be the variations 

 that occur among individuals or the variations that occur among 

 species, cannot explain themselves until we know the associated 

 correlative changes. No doubt, if we consider the enormous com- 

 plexity that there is in any of the higher organisms, the study of all 

 the correlations may seem almost a hopeless task. But if it be hope- 

 less, we believe that the problem of species will prove hopeless with it ; 

 and until the problem of correlation has been studied more fully, it 

 were idle to talk of hope or of the want of it. 



