Early Influence of Spermatozoan Characters of Echinoid Larva. 137 



formed in the blastula stage) with crinoid sperm (crinoid mesenchyme 

 formed in the gastrula) resulted in larvae which followed the maternal 

 course of development ; this was true even for the fertilized enucleated egg 

 fragment. 



In my own work a cross made on material with similar differences of 

 development, namely, the Cidaris egg (mesenchyme formed in the gastrula), 

 with Toxopneustes or Hipponoe sperm (echinoids in which the primary 

 mesenchyme is formed before gastrulation), gave larvse in which the mesen- 

 chyme was formed at the beginning of gastrulation, the mesenchyme arising 

 at the sides and base of the archenteron. 



We may ask this question : Is the foreign sperm better able to hasten 

 than to retard certain characteristic processes? It is not now possible to 

 answer this question, but it is one which should incite investigation. 



The objection may be raised that as I was unable to keep the hybrid 

 larvae alive beyond the gastrula stage, the cells which I observed passing 

 into the blastocoele were abnormal and indicated an abnormal condition 

 of the larvae. Certainly they were not normal Cidaris larvae; they were 

 hybrids, and as hybrids they were normal. The larvae were not the formless 

 aggregations of cells obtained in some crosses, but proceeded on a perfectly 

 regular course of development. Even granting that when compared with 

 larvae derived from straight fertilized Cidaris eggs, they were not normal, 

 it must be admitted that the abnormality was in the direction of normal 

 Toxopneustes mesenchyme formation and also that the condition was 

 brought about by the use of the foreign sperm and that the result indicates 

 that the sperm is able to exert an influence on the character of development 

 at a stage earlier than that heretofore demonstrated. 



Shearer, De Morgan, and Fuchs (191 1), as well as some other recent 

 workers on the hybridization of echinoids, have come to the conclusion 

 that the early larvae are of too variable a nature to afford any definite 

 evidence of parental influence. In order that I may not be misunderstood, 

 let me quote directly from the paper mentioned : 



As the result of extensive investigation of the early larval history of our various crosses, 

 we have come to the conclusion that these are too variable to afford any definite evidence 

 of parental influence and especially is this true with regard to the skeleton, heretofore 

 considered the chief index of inheritance. 



This conclusion was reached after the investigation of three species of 

 Echinus. The authors make the statement with regard to the forms upon 

 which they have worked and do not apply it to all cases. The investigation 

 of a sufficient number of properly chosen forms will convince any investigator 

 that parental influence may be indicated even in early larval stages, and 

 especially is this true with regard to the skeleton. 



