394 
which belong to lower levels and enjoy a longer tidal submersion. And 
as a matter of fact the poorer nutrition of the former is seen in their 
smaller size as well as in the different shape and texture of their 
shells. Now it is only after the young limpet has taken on its adult 
form and habits that the generative gland in each case begins to dif- 
ferentiate into ovary or testis. One might expect then that if nutri- 
tion has any influence on sex, such an influence would make itself 
seen in the different proportions of male and female specimens at 
different tidal levels, and in accordance with current theories it might 
be thought that the low-level limpets with their richer nutrition would 
show a relatively greater proportion of females over males. A a matter 
of fact however this is not found to be the case as the following figures 
may show. 
Female Male Hermaphrodite Percentage of Females 
High level limpets 55 23 1 69,6 
Middle , _,, 55 27 1 66,2 
Lows to. ates 59 25 1 69,4 
From this it will be seen that the percentage of females is practic- 
ally independent of tidal level, and the conclusion is that in the limpet 
more abundant nutrition does not predispose to the female type. On 
the other hand it seems well established that in certain types as the 
frog and the waterflea nutrition has a determining influence on sex. 
But it is interesting to note (1) that, as pointed out previously, the 
female sexual gland in the limpet is not larger in bulk than the male 
one, and does not therefore make special demands on nutrition, and 
(2) that, in the limpet there is an entire absence of secondary sexual 
characters as uterus, albumen gland etc. 
These are considerations to be taken into account in investigating 
the precise extent of the influence of nutrition on sex. The inference 
would be that quantity and richness of food tend to produce females 
only in those classes in which the female generative products are 
much greater in bulk and require more nutrition than those of the 
male as in the classical instances of the frog and the waterflea. 
But in the limpet, ovary and testis are equal in bulk, and there 
are no secondary structures through which the need for nutrition 
might make itself felt. As far as external indications go, the question 
of sex is here simply whether a certain tissue will produce ova or 
Spermatozoa. The results given above would seem to show that nutri- 
tion has no influence in deciding this question. One might infer that 
the same thing is true in all cases where the ovum approaches nearest 
its primitive form as a simple sexual cell apart from its secondary 
character as a storehouse for food material. 
