348 JOHN BEARD, 



The fifth row (20 sections) only reveals spinning ganglion-cells. 

 In the first row of the next slide (23 sections) there are two 

 large transient nerves 22 sections apart. 



In the following three rows of sections (70 sections in all) there 

 are no large "ganglionated" transient nerves, but there are still gan- 

 glion-cells on the cord, and here and there short nerve-processes. In 

 the third of these rows the presence of one or two longish fibres, 

 stretching along the outer side of the myotome, should be mentioned. 



The embryo is now just off the yolk-sac, and in the 

 following row of 28 sections there is a total cessation 

 of fibres and transient nerves to be recorded. 



This proves that, when the embryonic body leaves 

 the yolk-sac, the nerves of the system disappear. 



Of this series it may be stated in general terms that it is a good 

 one for demonstrating the transient nerves, which are as well repre- 

 sented as in No. 563. Sometimes, perhaps, the extension is not so 

 great, but both embryos (Nos. 563 and 564) differ remarkably from 

 No. 562. 



It may also be remarked of No. 564 that there is a marked 

 tendency among the transient nerves of this series to the formation 

 of plexuses, and numbers of small short fibres passing to the epiblast, 

 as in Fig, 76, are very apparent. 



As already mentioned, embryo No. 419 exhibits very similar 

 features to those recorded of embryo No. 410 ^). Like the latter it 

 possesses many subepiblastic nerves of the transient system, and here 

 also the nerves appear to pass in the direction of the yolk-sac. It is 

 quite an easy matter to trace many of them beyond the segmental 

 duct, often they are seen to lie closely under — even applied to — 

 the epiblast in their course. In this embryo all such nerves met 

 with were in the form of single fibrils without applied nuclei and 

 with no intervening ganglion-cells. 



One instance, out of many which might have been depicted, is 

 that shown in Fig. 72, Plate 25, 



The figure, like some already described, is a combination or re- 

 construction. Again in the sections the dorsal part of the cord pos- 

 sesses a crest or crown of transient ganglion-cells (gl. c. c). From 

 each side there project other ganglion-cells, which on the one hand 



1) page 340. 



