BIOGRAPHICAL SKKTCH OF HENRY MILNlT-EDWARDS. 721 



itself iu every part like ;i iiiyriapod, but this eoutbririity may vary from 

 different causes so as to constitute a multiplication of types. In cer- 

 tain families it happens sometimes that one or more of the zoonites 

 failing to perfect normally causes important modifications of form and 

 structure ui the others of the same family, and consequently among 

 neighboring zoonites. Sometimes the adjacent rings weld and mingle 

 together, this blending remaining marked by the ijcrsistence of certain 

 grooves or lines of less resistance; some among them lose at a certain 

 period the organs that existed at an earlier stage of life. In this way 

 the caudal fin of young crabs disai)pears in the adult. Crustaceans of 

 the i^arasitic order present in this respect the strangest suppressions 

 and malformations, retaining at the end of a certain period only the 

 organs of nutrition that are necessary to their jtarticular kind of life; 

 in compensation, also, sometimes becoming enormously developed. 

 These abortions, arrests of development, and atrophied parts not only 

 apjjear among the zoonites but also in their anatomical elements them- 

 selves. In fact each zoonite in turn is formed of several distinct parts 

 or sclerodermites, which also, by welding together, produce arrests of 

 development and atrophied members. In opposition to this it is observed 

 that the determinate part has an excessive development and a rela- 

 tive preponderance, for, Increasing in size, it extends and trespasses 

 upon neighboring parts. It multiplies itself, sometimes by a simple 

 repetition, sometimes by a redoubling, so to speak, of its typical j)arts. 

 But nature does not limit herself to a single process to attain her 

 end. It may also happen that this preponderating element grows by 

 a general development that is simultaneous and uniform throughout 

 the different parts. Thus there is an indefinite variety of natural com- 

 binations, all remaining subject to the limits of one same fundamental 

 type and to a kind of economy in processes and modified elements. 

 Crustaceans and marine animals of the lower orders in general offer a 

 most suggestive spectacle of these phenomena to the philosophic 

 mind. 



Nothing is more interesting than to survey, with Milne Edwards, this 

 extensive, at the same time homogeneous, group of crustaceans. From 

 them may be learned not only the form and the nature of organs but 

 the way these organs act; in other words, the study of structure is 

 always intimately connected with that of function and its offices. This 

 method is an innovation upon Cuvier's, which was to distribute the 

 animal kingdom strictly according to its organization — that is to say, 

 its anatomy. 



Milne-Edwards to a wonderful degree extended the limits of the zo- 

 ology of his time by introducing physiology as an essential part. This 

 was an original characteristic and one of the consequences of the new 

 method of study that he inaugurated in examining marine animals in 

 their own jdace and in a living state. 



The examination of the lower animals otters immense resources in 

 SM t)3 40 



