of the Fishery Board for Scotland. 



217 



of the tube enter the papilhi and give the origin of the tube a slightly 

 wrinkled appearance. In one case at least the tube was evidently con- 

 tinued into the papilla. 



In the larva of Scorpcena species, and in an unknown larva (probably 

 Osmerus species), the lateral papillai with their tubes were easily made out. 



These tubos have been described as palpocils. The reasons why I prefer 

 to regard them as tubes and not as sensory hairs are : — (1) That the sides 

 of the tube are always perfectly parallel, and the fibres are all parallel 

 to one another ; if they were simply palpocils they would certainly some- 

 times show a crossing and interweaving of the independent hairs ; (2) 

 when the tubes are bent backwards their shape and diameter are perfectly 

 retained — a condition which could not exist if the fibres were separate 

 hairs. 



What the function of these tubes may be it is difficult to understand. 

 I have in no case been able to make out any nerve supply. That they are 

 the rudiments of the lateral sense organs of the adult is more than doubtful ; 

 they are evidently not rudimentary organs, but subserve some function in 

 the larva; so elaborate organs for a sensory function in the larva would 

 appear superfluous. 



A not improbable hypothesis is that they act as exits to the fluid cir- 

 culating in the sub-epiblastic space. The papilla itself might be 

 regarded as a sort of sphincter to the tube. 



Excretory ("?) Products in the Gut. 



In an embryo of anchovy were seen small greenish granules, collected 

 in spherical masses, at certain points (c), in the gut, or isolated between 

 these points (c, fig. 19). The little masses are revolving at a rapid rate 

 at the places (marked c. in the sketch) where the gut shows slight 

 dilatations. The isolated c;ranules oscillate backwards and forwards — at 

 one time approaching, at another receding from the masses next them. 

 At each vortex, indicated by the motion of the masses of granules, there 

 is a group of cilia. The rectum is filled with similar granules. 



In a newly-hatched larva of anchovy the granules were seen to issue 

 from the anus ; in several larvae, granules similar to the above were seen 

 lying on the marginal fin outside the anus, while other granules were 

 present in the gut and rectum. 



In the larvae of Scorpcena species small granules were seen whirling 

 round in the wide intestine and in the rectum ; in the gut of the embryo 

 of plaice granular masses were seen ; while in the larva of whiting rod- 

 like bodies w^ere seen moving about in the rectum (r., fig. 17). 



Whence do these granules come? They are seen before the mouth 

 opens, and before there is a blood circulation. It is extremely improbable 

 that any digestion goes on in the gut ; but that excretory products are 

 formed in the embryo is undoubted. Certain changes take place — e.g., the 

 change or conversion of the non-staining yolk into the staining periblast, 

 the formation of cells and cell walls, and respiration. There must be ex- 

 cretion accompanying the growth The gut is the recipient of part of the 

 excretory products — viz., of respiration ; and it is not improbable that 

 other excretory products pass by osmosis from the growing tissues into the 

 gut, to be expelled by the anus. 



