Mr. H.J. Carter on the Spermatology of a new species of Nais. 97 



to the spermatozoa ; but with the complete development of the 

 latter, the functions of the granular mass cease, at the time that 

 those of the yelk chiefly commence. There is so little analogy, 

 then, between these two processes, that while they are sui generis 

 as regards each other, that producing the spermatozoa is, I think, 

 difl'erent from any other processes of cell-formation with which 

 I am acquainted. Of course I allude here to the attachment of 

 the spermatozoa to the albuminous sphere, and not to those in- 

 stances where the whole of the cell -contents of the spermatic or 

 mother-cell become divided up at once into a group of spermato- 

 phorous vesicles, each of which encloses from the beginning its 

 share of nourishment, and thus has no occasion for re-attach- 

 ment to an albuminous centre, as in some species of microscopic 

 FHarice. This is common enough among the Algae. 



Impregnation. 



This I have not seen, and therefore there is a hiatus here 

 which I cannot supply. Out of all the enlarged ova that have 

 come under my observation, not one has presented that broken- 

 down appearance of the granules of the yelk which follows im- 

 pregnation ; and although many have been bordering upon this 

 stage, yet it has been impossible to witness impregnation by 

 keeping the individual under the microscope, for the very pres- 

 sure of the slip of glass which is necessary to bring the ovunt 

 into focus kills the worm. Hence we must pass over that part 

 which intervenes between the development of the cells in the 

 germinal vesicle and the expulsion of the e^^, during which 

 time the germinal vesicle disappears, impregnation takes place, 

 the yelk-granules become dissolved or altered, and the ovum, 

 after having received its final investments, is laid. 



Development of the Embryo in Xais albida. 



It has already been intimated that all the information which 

 1 have been able to obtain respecting the development of the 

 embryo has been from the eggs of Xais albida, which were de- 

 posited in portions of a gelatinous Alga {Glwucapsa) that grows 

 on the sides of old walls and gutters in the island of Bombay, 

 during the rainy monsoon. By what means, in addition to the 

 contractile power of the delicate oviduct, the eggs are ex])elled, 

 I am ignorant ; but having frequently observed species of this 

 Nais with enlarged ova, in the midst of, and dragging them- 

 selves through, the gelatinous substance of the Alga mentioned, 

 to which the eggs arc thus agglutinated, it does not appear im- 

 probable that the resiliency of this substance may, to a certain 

 degree, assist the Nais during delivery. 



