MOKPHOLOGICAL METHOD AND RECENT PROGRESS IN ZOOLOGY. 607 



tical method, l)v no lueaiis now. I luno )>iit time to reeall to you the 

 presidential address of IS'IS ]»y m}' friend and pred(H'essor in this 

 cliair, himself a pioneer; and of the experlmcMital method T eaii but 

 eite an example, and that a most satisfactory one, justifying- our con- 

 tidence and support. It eoneerns the late Professor Milne-Edwards, 

 who in lS()4r deseri])ed, from the Paris Museum, the head of a rock 

 lol)ster {I'dl/HHnix 2><'>>(<''Uafns) havini;- on th(> left side an antenniform 

 eyestalk. With the perspicuity distincti\e of his ]-ac(\ he argued in 

 favor of the '* fundamental similarity of parts susceptible to revert to 

 theii- o})posite states." The matter remained at this till, on the 

 removal of th(> ophthalmite of certain Crustacea, it was found that in 

 regeneration it assumes a uniramous multiarticulate form, and it is an 

 interesting circumstance that in the connnon crayfish the biramous 

 condition normal to the antennule may occur — an example this of a 

 fact which nO other method could explain. 



When all is said and done, however, it is to the morphological 

 method that 1 would appeal as most reliable and soimd. And when 

 we tind (1) that in certain Compound Tunicates the atrial wall, in the 

 Ggg d(>velopment delimited by a pair of ectoblastic invaginations, in 

 the ]>ud development may be formed from the parental endodennic 

 branchial sac; (2) that regenerated organs are by no means derivative 

 of the l)lastemata whence they originally arose; (;')) that in the devel- 

 opment of a familiar starfish the inner cells of the earliest S(>gmenta- 

 tion stages, by intercalation among the outer, contribute half the fully 

 formed blastula; (4) that thertMire Diptera in existence in which, while 

 it is well nigh impossible to discriminate between the adult forms, 

 there is reason to believe the pupa cases an^. markedly and constantly 

 distinct, it becomes only too evident that the later embryonic and 

 adult states are those most reliable for all purposes of comparison, 

 and that it is by these that our animals can best be known and judged. 

 Caution is, however, necessary with senility and age, since certain 

 skulls have been found to assume at this period characters and pro- 

 portions strikingly a1)normal, and l)y virtue of th(^ most important 

 discovery, which we owe to the Japanese, that in certain Holothu- 

 rians the calcareous skeletal deposits may so change^ with age as to 

 render specitic diagnoses based on their pr(\sumed innnutability 

 invalid. Advance, real and progressive, is in no de})artment of 

 zoological inijuiry better marked than comparative morphology, and 

 it is for the preeminence of this that I would plead. Educationalh^ 

 it affords a mental discipline second to noin*. 



We live by ideas, we advance by a knowledgi' of facts, content to 

 discover the meaning of phenomena, sinc(> the nature of things will 

 be forever beyond our grasp. 



And now my task is done, except that I feel that we must not leave 



