CHAPTER FOURTH. 



EXAMINATION OF THE INVESTIGATIONS OF FORMER OBSERVERS. 



Eeviciv of 3Iiiikr's Observations. — It is with the greatest diffidence that 

 I enter upon this part of my subject. It seems the height of presump- 

 tion, for one who has scarcely any claim to recognition, to begin by 

 criticising so many statements of one of the great masters of our science. 

 Yet I hope to show, from Miiller's own figures, that the observations I 

 have made upon the development of our Starfish, though they do not 

 agree with his earlier memoirs, yet coincide entirely with a few figures 

 which he has given on the last plate of his great memoirs on the em- 

 bryology of Starfishes ; and that it is only because Miiller neglected the 

 earlier stages of develojsment, that he failed to arrive at the conclusions to 

 which I have been led by the above investigations. I trust that I have 

 succeeded in describing the successive stages in this development with clear- 

 ness enough to enable me now to draw a comparison, which the reader may 

 easily follow, with the last drawings made by Miiller, and to show that, 

 had he had the good fortune to see so complete a series as that which 

 I have traced, he would undoubtedly have entirely remodelled his former 

 views, with the same frankness which has characterized all his memoirs. 

 No preconceived theories, no observations, however careful, have ever 

 been allowed by him to interfere in the least with his subsequent obser- 

 vations. Hence the great difficulty of following Miiller in his intricate 

 discoveries ; each memoir modif\dng, correcting, and sometimes entirely 

 contradicting, the previous ones, so that we must, as it were, begin his 

 book at the end, in order rightly to understand his meaning. Any one 

 who has tried to follow the development of a single animal, so that noth- 

 ing should be wanting in the evidence of the successive stages, will easily 

 imderstand how later observations continually modify and explain what 

 had previously been considered as well understood. 



Although Sars was the first who followed the development of an Echi- 



