240 
RICHARD ASSHETOy. 
Feotogenesis or Kephalogenesis ? 
Deuterogenesis or Notogenesis ? 
I hope I have a desire no greater than is legitimate to 
support iny own view of processes etnbryological. 
I should, however, like to state clearly why I persist in 
using the terms “ protogenesis and “deuterogenesis” in 
preference to the terms coined by Professor Hubrecht, 
namely, “Kephalogenesis” and “Notogenesis,” which 
obviously refer to the same phenomena. 
I do so because Hubrecht’s words express conceptions, 
which, although having reference to the same phenomena 
which I wish to express by protogenesis and deuterogenesis, 
signify a different interpretation, which, in my opinion, does 
not represent the actual facts. And I would even claim some 
consideration because I believe that I was the first to recognise 
that protogenesis is in essence the production of a radial 
symmetry due to growth from one centre involving gastrula- 
tion, and that deuterogenesis is growth in length, bringing 
about bilateral symmetry and has nothing to do with gastrula- 
tion (though it may be an inevitable consequence of it), which 
conceptions I expressed at an earlier date under the terms 
primary and secondary growth centres (1894). Protogenesis 
and deuterogenesis form a, convenient paraphrase of those 
terms. 
On p. 63 Hubrecht claims to have been Avith Keibel the 
godfather of the unwarranted hypothesis that gastrulatiou 
occurs in two phases (Keibel, ’89, Hubrecht, ’88). 
Who claims actual parentage I do not know. But that it 
Avas a most mischievous and aAvkAvard child I can Avell 
believe. 
Fortunately both godfathers have fianlly disclaimed, b}' 
their papers in the year 1905 (^ Anat. Anz.,’ ‘ Quart. Journ. 
^licr. Sci.’), any further responsibility in their adopted off- 
spring, and they noAV admit that it is a matter of great 
importance in vertebrate embryology to distinguish betAveen 
