VARIATION IN ECHINOID PLUTEI 
679 
The work of the second section shows as type characteristics : 
Series I. Auric ularian type. 
Series II. Divided condition of anal arm. 
Series III. High percentage of normal larvae. 
Series IV. Weakness. 
Series V. Uncleft condition of pre-oral region. 
Series VI. Multiple rods in anal arms. 
The appearance of these characters suggests germinal varia- 
tions, but as I have pointed out before, they are of the nature of 
line or type variations. We are not, to be sure, dealing with 
pure lines in Johannsen's sense, nevertheless it is evident that the 
early development of these embryos shows a mean, which is not 
the mean of the general population of echinoid plutei, and each 
series or line exhibits its characteristic variations. 
The ability of the egg to impress its stamp on the embryo, is 
due, I believe, to its condition at the time of fertilization. I do 
not refer to a relative maturity of egg and spermatozoan, a con- 
ception that I cannot quite grasp, if the two are sufficiently mature 
to unite and develop, but to condition in the sense of tendency 
toward dominance. This condition is not fixed, but may be 
changed. (Tennent, 1910.) 
Viewed in this light, the mature egg, as it comes from the ovary 
and is passed into the sea water, carries with it a specific and an 
individual tendency. If fertilization be delayed and the egg sub- 
jected to factors changing its condition the chances of a dominance 
of paternal characters are greater. 
In conclusion I must urge most strongly that for any cross that 
is made with such organisms as we are discussing, a control be 
kept which will enable the investigator to determine the type 
variations occurring in the individuals with which he is working. 
