MR. BATESON ON VARIATION. 163 



The work has, however, much stronger claims on the attention 

 of entomologists, for the author has brought together a very 

 large number of instances of unusual structures and relations of 

 structures, while insects receive quite a fair share of attention at 

 his hands. As this latter feature is a departure from the usual 

 custom of "biologists," — who only too often in their considera- 

 tions either entirely omit reference to the most extensive and 

 zoologically important class of the animal kingdom, or treat it 

 in a fashion that is perhaps even worse than total omission, — 

 it is only proper that the work should receive from entomologists 

 an appreciative welcome, as we are sure will be the case when it 

 becomes known to them. 



Under the term *' Variation" Mr. Bateson includes a wider 

 range of facts than the word is usually made to cover ; a large 

 part of his work, indeed, refers to " monstrosities," which are 

 not generally treated as variations, though no doubt " sensu 

 latiori" they are such. A large number of these cases are 

 described by the author, who has had specimens entrusted to 

 him by various entomologists, foreign as well as English. As to 

 these particular sorts of variations he has been able to find some 

 interesting results, and, as might be expected, to discover that 

 order prevails even in this realm of apparent disorder. Sym- 

 metrical relations of a perfect kind are shown by close scrutiny 

 to be present in cases where, on superficial examination, such a 

 condition would be assuredly treated as wanting. Hence extra 

 legs and antennae form one of the most interesting sections of the 

 work. The extra wings of Lepidoptera — of which a number of 

 instances are described — have not, however, yet given any sign 

 of being anything but quite disorderly productions. 



Another interesting section to entomologists will be found 

 under the heading " Ocellar markings, especially those of Lepi- 

 doptera." Here the remarks of the author — particularly if they 

 be read in conjunction with Griffiths' and Urech's researches 

 during the last year or two — will be found very suggestive. 



There are very many forms of variation that are not touched 

 on at all in the present work, and we may express a hope that 

 the author will soon be able to treat these in another volume. 

 Colour variations, size difi'erences, and dimorphic and cyclical 

 forms are not here considered. Using the word "variation" in 

 a sense so wide as Mr. Bateson does, we think even secondary 

 and tertiary sexual distinctions should be included. Probably a 

 systematic review of the various morphological forms that may 

 be found in a single physiological species would, if well done, — 

 that is, if the species were well chosen, — be as interesting a 

 study in variation as could be made. The difficulties in the 

 way of carrying out such a review are, however, at present so 

 great that much time would have to be given to the adequate 

 performance of the task. Perhaps it was this consideration that 



