364 Prof. E. Claparede on the Reproduction of the Aphides. 



and the rather because, I repeat, the deseription of the blasto- 

 derin, as given by M. Balbiani, is correet in its chief points. 



In consequence of a multiphcation of the cells at the inferior 

 pole of the blastoderm, this gives origin to a protuberance, 

 which projects into the central vitelline mass. This protuber- 

 ance gradually increases in size, and subsequently plays an im- 

 portant part in the organogenesis; but we may remark at once 

 that, in proportion as the protuberance is developed, the vitel- 

 line mass diminishes by absorption, and finally even disappears 

 completely. 



One cell of the protuberance in question soon distinguishes 

 itself from the rest by its green colour, due to the appearance 

 in its protoplasm of a multitude of little coloured granules. 

 This cell multiplies itself rapidly, giving origin in consequence 

 to a mass of green cells, to which I shall apply the name 

 oi the green mass, so as not to prejudge its physiological 

 value. It will be seen already that this is the testis of M. 

 Balbiani*, the secondary vitellus of M. Meeznikow. At this 

 same period of embryonic life a group of cells is seen to de- 

 tach itself from the blastodermic protuberance and attach itself 

 to the side of the green mass ; and this will afterwards consti- 

 tute the blastogene or pseudovarium, as both M. Meeznikow 

 and M. Balbiani have proved. 



I pass rapidly over these remarkable phases of organogenesis, 

 because, with the exception of a few details, they have been 

 represented in a very similar manner by the two physiologists who 

 have led me to take up the pen ; but at this point it is desira- 

 ble to dwell upon some histological details, as upon these M. 

 Balbiani has raised his theory, seductive but, I think, radically 

 false, of the hemaphroditism of the Aphides. 



According to M. Balbiani the cells of the organ in question, 

 "when once penetrated by the fine granulations which give them 

 their green colour, generate in their interior a multitude of 

 small, pale daughter cells, furnished with a membrane and with 

 a nucleus, which he regards as cells of development of the sper- 

 matic elements. They are in fact soon replaced by innumera- 

 ble small dark corpuscles of 0*001-0 002 millimetre in 

 diameter, which, under a high power, appear "like very small 

 Amoeba;'^ but, adds the author, "their form does not seem to 

 change under the microscope.^^ " The mother cells,^^ continues 

 M. Balbiani, " have then lost their transparency and their green 

 colour; they have become opaque and brownish, and readily 



* M. Balbiani, properly s})eaking, represents this green mass as origi- 

 nating, not from the bhistodermic protuberance, but from the cylindrical 

 process, which, I have said, plays no active part in the development of the 

 ovum. I do not see that I can agree with him on this point. 



