285 



questions of classification and interpretation of structures are 

 discussed by Dr. E-olleston. There is a vast deal more, than 

 a mere expression of judgment as to the position which the 

 Gregarinse should occupy, in the above sentence. The corre- 

 lation of parasitism and degradation of structure, the claims 

 of convenience and of the principle of genealogy in classifi- 

 cation, the weight to be attached to polymorphism as against 

 individual development, arc all incidentally touched upon 

 with much advantage to the student. The constant reference 

 to and enunciation of principles deduced from general study, 

 forms one of the peculiarities of Professor RoUeston's teach- 

 ing, and where it may not be possible to agree Avith some of 

 these axioms, yet it is excellent for the j^upil to have such 

 briefly stated conclusions on which to thread his facts and 

 exercise his own powers of thought. We cannot commend 

 too highly the categorical way in which the most prominent 

 facts relating to the larger groups of the animal kingdom are 

 set forth. Dr. Rolleston follows Gegenbauer mainly in his 

 classification, and in describing the chief classes of vertebrata, 

 of mollusca, vermes, &c., gives such a body of knowledge as is 

 to be found in no other book — in the English tongue certainly 

 — besides copiovts references to recent and ancient authorities, 

 which will be valuable to the teacher and observer as well as 

 the class student. 



A further peculiarity of this book, which we would point 

 out, and which in our judgment gives it a special value, and 

 accounts for much of the freshness of its style, is that Dr. 

 Rolleston looks at forms of animal life as probably no other 

 distinguished anatomist of the day can do ; he looks at these 

 forms not as an artist ; he does not draw ; and he does not 

 accordingly treat morphology at all from the same point of 

 view as does the observer, who instinctively apprehends 

 and generalises a structure in a forcible sketch, as for example 

 Gegenbauer does. Though we have to regret on this account 

 the rather hard and unreal appearance of some of the wood- 

 cut figures in this book, over Avhich we know both draughts- 

 man and author spared no pains ; yet it is due to this same 

 cause that Professor Rolleston is so careful in his descriptions, 

 and so accurate in the use of language, an immense advan- 

 tage for the student. The style of treatment in this Avork is 

 rather by close and careful definition and detailed descrip- 

 tion, appealing to the logical faculty, than by diagrammatic 

 outlines and word-sketches, dependent on an artist's percep- 

 tion of form. Though we think it impossible to overestimate 

 the value of artistic power in the morphologist, it yet is 



