April 4, 1913] 



SCIENCE 



537 



ternal influence may be demonstrated in stages 

 even younger than the pluteus. I am now 

 able to show definite and clear-cut evidence of 

 such influence in the early gastrula stage. 

 This evidence will soon be published in de- 

 tail, so I shall give it here only in summary. 



The material from which this proof is 

 gained was obtained in February, 1911, while 

 I was working at the temporary station es- 

 tablished by the department of marine biol- 

 ogy of the Carnegie Institution in Montego 

 Bay, Jamaica, British West Indies. The re- 

 search involved the investigation of the nor- 

 mal development of Gidaris trihuloides and of 

 the hybrids obtained by crosses between 

 Cidaris, Hipponoe and Toxopneustes. 



In its normal development Cidaris is unlike 

 the modern Echinoids in that the primary 

 mesenchyme is formed late, the cells arising 

 23-26 hours after the fertilization of the egg, 

 from the inner end of the archenteron, which 

 has pushed, by this time, well into the blasto- 

 ccele. ISTo mesenchyme cells appear during the 

 blastula stage. In Toxopneustes, as is well 

 known, the primary mesenchyme cells arise 

 about 8 hours after the fertilization of the 

 egg, at the posterior pole of the blastula and 

 have passed into the blastocoele before the be- 

 ginning of the invagination of the archenteron. 

 A similar condition holds for Hipponoe. 



In the Cidaris ? X Toxopneustes d and the 

 Cidaris ? X Hipponoe <? crosses, gastrulation 

 begins in about 23 hours after fertilization, as 

 in the straight fertilized Cidaris eggs, the 

 process not being noticeably hastened by the 

 use of the foreign sperm. The primary mesen- 

 chyme appears about one hour later, the cells 

 arising around the base of the then very short 

 archenteron, at the region of the lips of the 

 blastopore. 



The influence of the foreign sperm is thus 

 clearly shown in the changed site of mesen- 

 chyme formation. Furthermore, it appears 

 ontogenetically earlier in the hybrids than in 

 the normal Cidaris larvaj. 



In calling attention to these matters I do 

 not wish to disparage in any degree the work 

 being done by Shearer, De Morgan and Fuchs 

 and the other British zoologists who have re- 



cently begun work in this field. Their work 



on the later stages is admirable. I do wish to 

 plead against the acceptance of negative evi- 

 dence as the basis for a positive generaliza- 

 tion concerning the early stages in Echinoid 

 crosses. Well-chosen material may give posi- 

 tive evidence. 



David H. Tennent 



SOCIETIES AND ACADEMIES 



THE ACADEMY OF SCIENCE OP ST. LOUIS 



At the regular meeting of the Academy on Feb- 

 ruary 3 and 17, the following papers were read: 



Dr. C. H. Turner:' "Apparent Eeversal of the 

 Light Responses of the Common Eoach. ' ' 



Dr. LeRoy MoMaster : ' ' The Preparation and 

 Properties of the Ammonium Salts of Some Or- 

 ganic Acids. ' ' 



Dr. Leo Loeb : ' ' Some Biological Aspects of 

 Tumor Investigation." 



Dr. Turner discussed a series of experiments 

 conducted with the common roach {Periplaneta ori- 

 entalis) for the purpose of seeing if a negatively 

 phototropic animal could be trained to refuse to 

 enter a specific dark place ; and, if that proved 

 possible, for the additional purpose of obtaining 

 an experimental analysis of the behavior. 



The electrical punishment method, devised by 

 Professor Yerkes in his study of the dancing 

 mouse, was used. 



The speaker stated that he had trained roaches 

 of both sexes and different ages to avoid a specific 

 dark pla«e, and insisted it was equally as logical to 

 interpret his results by concluding that the roach, 

 by means of associated memory, had learned to 

 avoid a specific dark place, as to term its behavior 

 a reversal of negative phototropism. 



Professor McMaster described a method of pre- 

 paring the neutral ammonium salts of monobasic 

 and dibasic organic acids, by dissolving the acids 

 in absolute alcohol or ether and passing dry am- 

 monium gas into the solution. There easily re- 

 sulted the neutral ammonium salts of succinic, tar- 

 taric, ortho- and meta-phthalic, propionic, isobuty- 

 ric and benzoic acids. Malonic, malic and einnamie 

 acid salts resulted with difKeulty. Analyses showed 

 the compounds to be neutral.^ 



^Biological Bulletin, Vol. XXIII., 1912, pp. 371- 

 386. 



^ This paper will appear in the April number 

 of the American Chemical Journal. 



