358 Blackman . — On the Fertilization , Alternation of 
that in the case of the lower organisms, the effect of a division, presumably 
unequal, of the nature of amitosis might be long delayed ; and in the case 
of the higher plants might not be visible immediately. It seems quite 
possible, however, that even in the case of the higher plants a change 
might be produced which would not be observable at all in the ordinary 
restricted life-history of cells other than the germ-cells. We have no 
knowledge as to how unequal an indirect division may be in relation to 
the chromatin ; no doubt the degree of inequality must be very variable (it 
may probably be sometimes as equal in effect as indirect division), but it is 
quite conceivable that the change produced by a direct division in the 
c hereditary properties 5 of, say, a root-cell may be confined to those con- 
cerned with flower or leaf development, and so never be visible in the normal 
course of development of a root-cell. 
The beautiful experimental researches of Boveri (9) on double fertilized 
eggs of the Sea-urchin (in which he practically proves the existence of 
physiological individuality in the chromosomes) lend strong support to such 
a view, for certain blastomeres of the three- or four-celled stage, though 
capable of normal division and apparently similar to the other blastomeres, 
were found later to be deficient in the power of producing certain organs 
(such as the skeleton, pigmentation, &c.), owing to the unequal sorting of 
the chromosomes in the first division. 
It is clear however that in the case of the intercalation of an amitotic 
division in the series of divisions leading directly up to the germ-cells, such 
as that described by Meeves (32) and Macgregor (31) for the spermatozoa 
of Amphibians, the effect of any inequality of division would produce an 
effect, sooner or later, in the offspring. If such a division be confirmed it 
seems hardly possible to consider it as other than a true equational one of 
equal value with mitosis ; at least if the ordinary view be accepted as to 
the meaning of chromosomes and their splitting. There seems to be some 
doubt, however, as to whether this form of division is regularly present. 
Sutton (52) has also suggested that, as the amitotic division in these cases 
does not apparently lead to cell-division, it may be that the two nuclei meet 
again on the spindle of the next mitosis, and so the direct division is 
without effect. 
The view may perhaps be hazarded that the sufficiency for the cell 
needs of the Uredineae of such a simple method of division may be connected 
with the simple organization of such forms as compared with the higher 
plants ; the ‘ idioplasm 5 must be far less complex. 
Alternation of Generations. 
If the view be accepted that the spermogonia and aecidia represent 
male and female organs respectively (and the observations in Phragmidium 
appear to leave no escape from such a view) it is clear that the Uredineae 
