508 
ota. In the same way as in Annelida the rudiment of the stomodaeum 
(Wirson, 1892, DersmanN, 1916), so in Vertebrata the rudiment of the 
medullary canal (without the cerebral plate) lies in a crescent round 
the anterior border of the blastopore. The maximum breadth of this 
crescent continually increases during the closing of the blastopore 
and ultimately becomes the longitudinal axis of the medullary plate. 
[ made different pricking experiments also during the closing of the 
blastopore, on which I shall not dwell here, since they did not lead 
to results deviating from those obtained by my predecessors AssHETON, 
1894, MorcaN and Umk Tsupa, 1894, Eryceresnymer, 1898, Winsor, 
1900, Kine, 1902. They confirmed the above conception. 
That the closure of the blastopore is identical with the gastrula- 
tion of the Chordata will not be doubted by any one who has 
occupied himself with the gastrulation process in different. groups of 
Evertebrata. Still I wish to emphasize this, since on the question 
what gastrulation in the Chordata really is, opinions have recently 
been put forth and accepted, also in my country, which I think 
must be entirely rejected. So Husprecut (1905) and Bracuer (1905), 
following AssuETON, support the conception that the gastrulation (in 
the form of a delamination) would be completed already when the 
first blastopore lip appears and that the closure of the blastopore 
— by concrescence, according to the former two — is entirely independent 
of the gastrulation, but according to Husrecut would correspond to 
the conerescence of the buccal slit of an actinia (theory of SEDGWICK- 
LAMEERE). For this process the name notogenesis is introduced and 
the blastopore is henceforth called notopore. Some compatriots of 
a younger generation (Borkr, 1907, pr Lance, 1907, Laine, 1913) 
have accepted this nomenclature together with the conceptions of 
the. lately deceased nestor of Dutch embryologists. As has already 
been stated, I cannot agree with these and other conceptions of 
Husrecur, however cleverly they combine ideas borrowed from 
Lworr, Hrrtwic, VAN BENEDEN and others, if it were only since in 
my opinion nothing pleads for and everything against concrescence, 
while moreover it has been sufficiently demonstrated that not 
at all the whole of the medullary plate, as Bracner thinks, or the 
epichordal part of it, as HusBreenr assumed, is formed over the 
blastopore. My own conception about the gastrulation process 
of the anamnia is evident from the preceding pages, which 
moreover show how excellently the results of the later investigations 
agree with the conclusions arrived at by my theory. 
Is the cerebral vesicle of Amphioxus homologous with the brain 
of the Craniota? This question I put in a preceding paper (1913, b). 
