Apkil 21, 1922] 



SCIENCE 



431 



in a chair and asked me to tie him in place. 

 So well did I tie him that we had to cut him 

 out afterwards. Then he fell into a trance, 

 and suddenly I became aware of dazzling celes- 

 tial lights over his head. Then my son's voice 

 cried out: 'Father, father.' The voice was not 

 a yard from my face. 



"Yes, my boy," I answered. "Yes, what 

 is it?" 



" 'Father ! Pardon !' he said, and I felt his 

 hand on the top of my head, bowing down my 

 head, and then felt his lips touch my forehead. 



"I knew what he meant immediately. Only 

 I could have known. He had never subscribed 

 to my belief while alive, and now he had come 

 back to tell me that it had been as I said. 



" 'Yes, my son,' I called back to him, 'you 

 had a right to your own belief while here 

 with us.' " 



Again the speaker, wrought up to a high 

 pitch, cried : 



"If that isn't spiritual communication, what 

 is it?" And the audience, listening intently to 

 every word, broke out in a clatter of applause. 



SCIENTIFIC BOOKS 



Studies of the Development and Larval Forms 

 of Echinoderms. By Th. Mortensen. 266 

 pages, 33 plates and 102 text-figures. Pub- 

 lished at the expense of the Carlsberg Fund. 

 G. E. C. Gad, Copenliagen, 1921. 

 For some years, the well-known Danish zool- 

 ogist. Dr. Th. Mortensen, has been gathering 

 material in the embryological field to use in 

 throwing light on the phytogeny of the echino- 

 derms and on the interrelationships of families 

 and genera in the most perplexing groups. A 

 two year's journey around the world including 

 stays of several weeks or more at Zamboanga 

 and Jolo in the Philippines; Misaki, Japan; 

 Sydney, N. S. W. ; New Zealand; Hawaii; 

 Nanaimo, British Columbia; La Jolla, Califor- 

 nia; Taboga Island, Panama; and Tobago, 

 B. W. I., resulted in such an accumulation of 

 material that the present noteworthy report 

 has been prepared and published. Yet the 

 indefatigable Danish investigator is again afield 

 in search of more material and at the same 

 time is hunting out tlie best place in the East 



Indies for the establishment of a permanent 

 Scandinavian marine biological station! 



As one turns the pages and studies the plates 

 of this great contribution to embryolog3', it is 

 hard to decide whether one should admire the 

 more the industry, patience and skill of the 

 investigator, or the ability to marshal his facts 

 and set forth clearly his conclusions, revealed 

 in the writing. Descriptions and figures alike 

 leave nothing to be desired and even if one 

 were not to accept all the suggested conclusions 

 one can not question the care or the fairness 

 with which they are expressed. 



An introduction of 19 pages gives a brief 

 Init clear summary of what has so far been 

 accomplished in acquiring knowledge of the 

 embryology of those echinoderms which have 

 free-living larval forms. Including Morten- 

 sen's own results we now have such knowledge, 

 often very fragmentary it must be granted, of 

 some 125 species. Thei'e is also much material 

 accumulated concerning the life histories of 

 many species which do not have free-living 

 larvffi, but these are not included within the 

 scope of the present report. The main purpose 

 of Mortensen's research has been, to quote his 

 own words, to throw light on "the interrela- 

 tion between the larvaB and the adults in regard 

 to a natural classification." 



The second section of the report, designated 

 "Special Part," deals with the larva; of more 

 than sixty identified species and nearly fifty 

 additional larvse, whose parent forms are un- 

 known. No crinoids are discussed, as Dr. Mor- 

 tensen has published his studies on crinoid 

 development elsewhere. As experience demon- 

 strated that the eggs of echini are more easily 

 fertilized artificially than are those of other 

 echinoderms, it is not surprising that nearly 

 three fourths of Mortensen's work was done 

 on members of that class, at least so far as 

 results reveal. The early stages of no fewer 

 than 43 species were studied and many 

 species were carried along thi-ough weeks 

 and sometimes months of larval life. One of 

 the interesting results of this work was the 

 demonstration of the hardiness of the larva; of 

 certain species. Thus some larvae of the com- 

 mon West Indian rock-boring urchin (Echino- 

 metra liicunter), hatched from eggs fertilized 



