ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 831 



respiratory water, and which, is directed towards the oesophageal 

 mouth. In structure, the gland is altogether similar to those small 

 glands which are scattered over the buccal walls of higher Vertebrates, 

 and which secrete mucus. Yet again, the author finds additional 

 support for his view in the fact that mucus-filaments may often be 

 seen attached to the edges of the gland, or within the cavity of the 

 vibratile canal. On the other hand there is no evidence to support 

 the view that the cells of the raphe or of the pericoronal groove 

 secrete the mucous filaments. The observations here recorded were 

 made on adult specimens of Phallusiidse, and the author purposes to 

 make embryological investigations to see if they support the homo- 

 logical views to which he at present inclines. 



Alteration of Ascidian Ova.* — We have here another essay from 

 A. Sabatier in which he studies the characters of the yellow cells 

 which he has already noted in the follicular cells of the ova of some 

 Ascidians. When an ovary of Phallusia mamillata or P. cristata is 

 teased out on the slide we find a large number of ova which are pro- 

 vided with an amorphous capsular envelope, a single layer of follicular 

 cells, and a mass of yellow substance, which varies in form and lies 

 in the centre of a clear, hyaline, and altogether colourless substance. 



The follicular portion is clearly arrested in development, while 

 that which most attracts the observer is the variable yellow mass 

 within. This last is not dissolved by caustic potash or coloured 

 characteristically by Millon's reagent: nor does it seem to be of a 

 starchy nature. When, however, the granules are treated with strong 

 acids they give off carbonic acid, and further use of appropriate 

 reagents shows that we have here to do with oxalate of calcium. No 

 definite judgment has yet been arrived at as to the characters or origin 

 of the yellow colouring matter. 



The action of colouring matters leads to the belief that the yellow 

 masses are formed of collections of spherocrystals of carbonate of 

 calcium, produced by the deposition of small crystals which radiated 

 around primitive nuclei, arising either from the original nucleus, or from 

 centrifugal and perinuclear corpuscles. They may be compared to the 

 cystoliths which one observes in the cells of certain plants, with the 

 difference that the organic stroma is here formed from the nucleus, 

 and not from the investing membrane of the cell. 



The fact that these altered ova are rare in young and more 

 numerous in older individuals leads us to suppose that we have here 

 to do with a phenomenon of senile alteration, the effects of which 

 increase with age, and lead, so to speak, to a gradual disappearance of 

 the effective sexuality of the animal. At any rate, they are only 

 found when the sexual role has disappeared, and their presence in an 

 anatomical element is a sign of the disappearance of the sexuality of 

 that element, whether that be male (foUiculai cells, celluloid globules) 

 or female (nucleus, nucleoli, portions of the ovarian protoplasm). 



* Eev. Sci. Nat., ii. (1883) pp. 587-95. 



