THE "GENERAL MORPHOLOGY" 249 



series at London, as the 28tli volume of the 

 Zoologij of the Challenger, 1888. The voluminous 

 work is illustrated with fifty masterly plates, some 

 of them coloured, by Haeckel himself. The most 

 important part of the text was also published in 

 German at Jena, with the title, System of the 

 SiphonophorcE. There is a good popular account 

 of the siphonophore question in his lecture on 

 ** The Division of Labour in Nature and in 

 Human Life" (1869). A few of these beautiful 

 forms are also given on coloured plates in his 

 illustrated work, Art-forms in Nature. Every 

 thoughtful man ought, whatever his position is 

 as regards HaeckePs ideas, to glance at this 

 material that he has so vigorously and clearly 

 presented. 



While he was conducting this research into 

 the embryonic development of the siphonophores, 

 Haeckel made certain experiments on phenomena 

 that have lately been made the subject of a special 

 *' experimental mechanical embryology" by some 

 of his pupils, particularly Professor Eoux, of Halle. 

 He cut up siphonophore ova into several pieces at 

 the commencement of their development, and saw 

 an incomplete social medusa develop from each 

 fragment. 



Thus the journey, like the earlier one to 

 Messina, brought the indefatigable student into 

 touch once more with a " philosophical animal." 

 This alone would have made it well worth the 

 trouble. How many more of the kind the future 

 might still have in reserve for him ! In the quiet 



