290 HAECKEL 



comprehensive work. The chief contents of the 

 English work (with a selection of the plates) were 

 then published in German, and appeared in 1887 

 and 1888 as the second, third, and fourth parts 

 of the Monograph on the Radiolaria. A sort of 

 supplementary essay on the methods of studying 

 the radiolaria and cognate " planet on" animals was 

 published separately with the title of Planctonic 

 studies (1890). Though it was a moderate and 

 tactful criticism of the methods of some of his 

 colleagues in this kind of work, it was " refuted" 

 by them in a way that it would be diffici^lt to 

 qualify in other words, it was fruitlessly assailed 

 with charges of the most general but most un- j 

 pleasant character. In the English Eeport we find 

 two other volumes afterwards from Haeckel the 

 volume on the siphonophorae in 1888, and the 

 Report on the Deep-sea Keratosa collected by H.M.S. 

 Challenger in 1889 ; these again opened up new 

 chapters in zoology. The Challenger work is the 

 crown of Haeckel's studies as a specialist. To some 

 extent the conclusion of it closes an epoch in his life. 



We will only touch briefly on what he has done 

 since. It has not yet passedinto the region of history. 



The latest years in Haeckel's constructive work 

 are characterised mainly by one idea. He had 

 often been pressed to work up afresh the material 

 of his General Morphology. He has not done so in 

 the form that was expected, but chose a form of 

 his own. In the first place he took the systematic 

 introduction to the second volume, which had been 

 the first able attempt to draw up the genealogical 



