602 PROFESSOR MARCUS HAUTOG. 



to ensure od the one liand a sufficiently large amount of cyto- 

 plasm and reserves to the young-, and on the other enough 

 mobility on the part of one gamete to ensure its finding the 

 other and to favour crossing. 



A very remarkable t^^DC of syngamy was first discovered 

 by Boveri, as long ago as 1889. He found that the egg of 

 Echinidsj when shaken up, divides into fragments, only one of 

 which can be nucleated; that sperms enter whether these 

 contain the nucleus or uo ; and that development follows in 

 either case. These experiments have been recently taken up 

 and extended, notably by Delage, who has given the name of 

 " merogony " to the process. Griard, however, has regarded 

 it as really a parthenogenesis of the male which, when 

 reduced to a differentiated sperm, has not sufficient cytoplasm 

 for independent life. However, this assumes that the cyto- 

 plasm plays no part of its own in cell-life, but lies absolutely 

 under the despotism of the nucleus — a view for which evidence 

 is absent. True this differentiated sperm has but a minute 

 investment of cytoplasm, but, such as it is, it in Metazoa con- 

 tains thecentrosome, and may in other respects as in this have 

 the power of growing within the egg at the expense of the 

 female cytoplasm and reserves during the very process of fusion 

 therewith. Male parthenogenesis, strictly speaking, can only 

 exist where the sperm is slightly smaller than the oosphere, 

 the binary sexual differentiation is not too complete ; and the 

 term should be reserved for such cases of what may be called 

 " anisogamy," which are notably to be found in certain Algas. 



Lankester regards the independent germination of small 

 zoospores as a case of male parthenogenessis, in cases where 

 they never show any signs of pairing, and occur in a distinct 

 stage of the life-cycle, as in Hajmatozoic Coccidia; but this 

 seems to be an inversion of the facts. For pairing-cells 

 assuredly, originated from indifferent zoospores, which germ- 

 inate independently; and where there is no symptoms of audi 

 zoospores being sperms gone wrong, we are not justified in 

 supposing it. 



