97 



opening. A somewhat unusual circumstance in connection with these 

 organs is that, in Eupomatus at least, they serve not only as efferent 

 ducts for the generative products, but as seats of development of the 

 ova. In that genus I have found in the cavity of each segmental 

 organ a little clump of ova in all stages of development, closely adhe- 

 rent together and rotating or moving to and fro under the action of the 

 cilia ; alternating with the segmental organs were the ovaries proper 

 consisting of clumps of ova in various stages of development and 

 occupying the normal position in the perivisceral cavity. In the male 

 specimens which I have examined I have always found the sacs empty. 

 Sydney, 17. October 1884., 



2. On the fate of the Blastopore in Rana temporaria. 



By W. Baldwin Spencer, Scholar of Exeter Coll., Oxford. 



eingeg. 3. December 1884. 



The following is a brief outline of the results arrived at during 

 an investigation into the fate of the blastopore in Itana temporaria: 

 I hope to publish a more complete account with figures elsewhere. 



As is well known a neural groove is present in the] frog's ovum 

 traversing the whole length of the medullary plate^and reaching as far 

 as the blastopore posteriorly. 



It is usually stated that the medullary folds extend behind (poste- 

 rior to) the blastopore and that, when they grow over, meet each other 

 and enclose the neural canal, the blastopore also is enclosed and a neur- 

 enteric canal is formed. The conclusions at which I have arrived 

 from the study of numerous series of consecutive sections cut by means 

 of Caldwell's Microtome are: 



1) The medullary folds grow over and enclose the neural canal 

 but not the blastopore which remains open to the exterior: 

 the neural canal however reaches back as far as the blastopore and 

 opens into this. 



2) The hinder part of the neural canal which opens into the blasto- 

 pore loses its cavity and the nervous system in this region becomes 

 solid. 



3) In the same region (that is just in front of the blastopore) the 

 epi-, meso- and hypoblast are fused together. 



4) The Blastopore never closes but becomes transformed 

 into the adult anus. 



Miss Johnson has recently shown* that in the Newt the blasto- 



1 Quart. Journ. Micr. Sci. Oct. 1^ 



